Option 2, Linked List, is the best-suited data structure for implementing a stack. This is because a stack requires constant time operations for push and pop operations, which can be efficiently achieved using a linked list's dynamic memory allocation and pointer manipulation.

An Intrusion Detection System (IDS) plays a crucial role in network security by monitoring network traffic for any suspicious or malicious activity. It doesn't prevent all cyberattacks but rather detects potential threats in real-time, providing alerts to administrators so they can take appropriate action to mitigate the risk. IDS helps in identifying unauthorized access attempts, anomalies in network traffic, and other security breaches, contributing significantly to overall network security posture.

React.js is primarily used for building user interfaces in web development. It allows developers to create interactive and dynamic UI components that update efficiently when data changes. React.js focuses on the frontend aspect of web development, handling the visual presentation and user interaction of web applications.

The "Content-Type" header in RESTful API requests specifies the format of the data being sent in the request body. For example, it can be "application/json" for JSON data or "application/xml" for XML data.

The Iterative SDLC model involves revisiting and refining work in multiple cycles, allowing for feedback incorporation and continuous improvement. On the other hand, the Incremental SDLC model delivers functionality in increments, providing tangible value early and enabling progressive development.

Secure RESTful APIs employ various mechanisms to protect data and authenticate clients. SSL/TLS encryption ensures that data transmitted between clients and servers is encrypted, preventing unauthorized access and eavesdropping. OAuth 2.0 is a popular authorization framework that allows secure token-based authentication, enabling clients to access resources on behalf of users without exposing sensitive credentials. JWT (JSON Web Tokens) are used for securely transmitting information between parties as compact, URL-safe tokens, facilitating stateless authentication and authorization in RESTful architectures. IP whitelisting restricts access to API endpoints based on predefined IP addresses, enhancing security by allowing only trusted clients to interact with the API. Each of these mechanisms plays a vital role in safeguarding RESTful APIs against common security threats such as data breaches, unauthorized access, and man-in-the-middle attacks.

The design pattern used to ensure a class has only one instance and provides a global point of access to it is the Singleton pattern. This pattern restricts instantiation of a class to a single object and provides a way to access that instance globally. It is commonly used in scenarios such as database connections, logging mechanisms, and configuration settings where having multiple instances can lead to issues like resource wastage or inconsistent behavior.

In a doubly linked list, each node contains references to the next node and the previous node. This is because each node has two pointers, one pointing to the next node and one to the previous node.

A database system ensures durability, one of the ACID properties, by using techniques like Write-Ahead Logging (WAL). In WAL, before modifying data in the database, the system first writes the changes to a log file on disk. This log file acts as a record of all transactions, and in the event of a system failure, the database can recover by replaying the logged transactions from the log file to restore the database to a consistent state. This ensures that even if the system crashes, committed transactions are not lost and the database remains durable. Other techniques such as checkpoints and transaction logs also contribute to ensuring durability in database systems, making them robust against failures.

In a priority queue, elements are dequeued based on their priority level, where higher-priority elements are dequeued before lower-priority elements. Priority queues are often implemented using heaps to efficiently maintain the highest priority element at the front.