Socket.io is a reliable choice for developing real-time chat applications. It enables bidirectional communication and supports WebSocket, making it efficient for handling real-time updates in a chat system.

Role-based access control (RBAC) is a common method for authorization in large systems. It defines access levels based on a user's role within an organization. The correct option aligns with the purpose of RBAC.

The principle of least privilege in security advocates restricting users' access rights to the minimum necessary for their job functions. This minimizes the potential damage from accidental mishandling or intentional malicious actions.

Node.js, based on JavaScript, is known for its scalability and event-driven architecture. It is commonly used with frameworks like Express.js for building efficient server-side applications.

Git is a Version Control System (VCS) that enables multiple developers to collaborate on a project efficiently. It tracks changes in source code during software development, allowing teams to manage and coordinate their work.

Closure scope is created when a function is defined inside another function. It allows the inner function to access the outer function's variables, even after the outer function has finished executing.

Feature Branching is a common branching strategy where developers create a new branch for each new feature they are working on. This approach helps in isolating changes related to a specific feature and facilitates parallel development.

Indexing the relevant columns is a key strategy for optimizing database queries. It helps speed up data retrieval by creating efficient access paths to the required information, reducing query execution time.

OAuth primarily focuses on delegated access to resources. It allows one service to perform actions on behalf of a user, without exposing their credentials.

The INSERT SQL command is used to add a new row to a database table. It allows you to insert data into a specified table.