Prioritizing testing based on risk assessment ensures that critical functionalities are thoroughly tested, reducing the likelihood of critical defects escaping into production. This approach also helps in allocating resources effectively during the testing phase.

React.js is the web framework that uses a virtual DOM for efficient rendering. The virtual DOM is a programming concept where an ideal or virtual representation of a UI is kept in memory and synced with the "real" DOM by a library such as React.js. This approach helps improve performance by minimizing DOM updates and rerenders, making React.js a popular choice for building fast and responsive user interfaces.

The correct answer is 'padding.' Padding is used to create space between the content of an element and its border. It can be specified using different units such as pixels, percentages, or ems.

A primary key uniquely identifies each record in a table and ensures that there are no duplicate values. It also automatically creates a unique index for fast data retrieval. On the other hand, a foreign key establishes a relationship between two tables, ensuring referential integrity and enforcing data constraints.

The correct option is "Portability." Containerization encapsulates applications along with their dependencies, libraries, and configurations into portable units called containers. This portability allows containers to run consistently across different environments, making application deployment and migration easier. It also enhances collaboration and agility in software development and deployment processes.

Maintaining ACID properties in distributed databases involves trade-offs compared to centralized databases. One major trade-off is the balance between consistency and availability. In distributed systems, ensuring strong consistency across all nodes can lead to increased latency and potential scalability challenges due to the need for synchronous communication and coordination. On the other hand, prioritizing availability may sacrifice consistency, leading to eventual consistency models where data may be temporarily inconsistent across nodes. Additionally, network partitioning issues can arise in distributed databases, affecting the system's ability to maintain ACID properties uniformly. These trade-offs require careful consideration and architectural decisions based on the specific requirements of the application and the desired level of data consistency and availability.

Dynamic programming is based on the principle of breaking down complex problems into smaller, manageable subproblems and solving each subproblem just once, storing the results for future reference. Memoization is a technique used in dynamic programming to store previously computed results to avoid redundant computations, making it an essential aspect of this approach.

Authentication involves verifying the identity of users or devices, ensuring they are who they claim to be. Authorization, on the other hand, deals with granting or denying access to resources based on the authenticated identity and specified permissions. While authentication establishes trust, authorization controls the level of access granted.

The "Optimal Substructure" property in dynamic programming states that the optimal solution to a problem can be constructed from optimal solutions to its subproblems. This property enables subproblems to be solved independently and then combined to solve the overall problem efficiently.

In multitasking operating systems, the mechanism used to switch between processes is known as a context switch. A context switch involves saving the state of a currently running process, including its registers, program counter, and other relevant information, and then loading the state of the next process to be executed. This allows the operating system to efficiently allocate CPU time among multiple processes, enabling concurrent execution and multitasking capabilities. Understanding context switching is crucial for system performance optimization and multitasking efficiency.

The Decorator design pattern allows behavior to be added to individual objects dynamically, while inheritance creates a static hierarchy of classes where subclasses inherit behavior from their parent class. The Decorator pattern promotes code reusability and flexibility.

To revert a commit in Git without losing the changes, you can use the git revert command. Unlike git reset, which can remove commits and potentially lose changes, git revert creates a new commit that undoes the changes introduced by a specific commit. This maintains a clean history and preserves the changes made in subsequent commits. The git revert command is especially useful when working in a collaborative environment where rewriting history can cause conflicts for other team members. It allows for a safer way to undo changes while keeping the project history intact.