SQL indexes are used to improve data retrieval speed by creating a sorted reference to data in a table. This reduces the time required to search and fetch specific records, especially in large datasets. Indexes don't impact storage space significantly but rather optimize data access, ensuring faster query performance. Indexes also contribute to enhancing data security by facilitating efficient data retrieval for authorized users.

The correct option is Implementation. This phase is where the actual coding takes place based on the design specifications developed in the previous phases. Developers write, compile, and debug the code to ensure it meets the defined requirements. Additionally, testing activities are initiated during this phase to identify and fix defects early in the development process. Once the implementation phase is complete, the software is ready for testing and quality assurance processes before deployment.

Data normalization includes breaking down large tables into smaller ones and establishing relationships between them. This practice enhances data organization, reduces redundancy, and facilitates efficient data management and retrieval.

The correct option is "SMTP," which stands for Simple Mail Transfer Protocol. SMTP is a protocol used for sending and receiving emails over the Internet. It works in conjunction with other protocols like POP3 or IMAP for email retrieval and delivery. SMTP facilitates the transfer of emails between servers and enables communication between email clients and servers.

In Priority-based scheduling, processes are executed based on their priority levels, with higher-priority processes being selected over lower-priority ones. This ensures that critical tasks or processes with urgent needs are handled promptly.

MAC filtering in wireless networks is primarily used for controlling device access. It works by allowing or denying network access based on the MAC addresses of devices trying to connect. This helps in enhancing security by only allowing authorized devices to join the network, preventing unauthorized access.

Graph databases are specifically designed to handle highly interconnected data. They excel in managing complex relationships between different entities by representing data as nodes, edges, and properties, making them ideal for applications like social networks, recommendation engines, and network analysis. Other NoSQL databases may struggle with efficiently querying and traversing interconnected data structures compared to graph databases.

Multilevel Queue Scheduling involves categorizing processes into different queues based on their characteristics, such as priority, CPU burst time, or I/O requirements. The "Ready Queue" is where processes are placed after being sorted into appropriate levels, ready for execution.

When a resource is successfully created in a RESTful API, it typically returns a status code of 201 Created. This indicates that the request was successful and a new resource has been created on the server.

One way to check if a string is a palindrome is to compare it with its reversed version. This can be achieved by reversing the characters of the string and then comparing the original string with the reversed one. If they are equal, the string is a palindrome. Using arrays and strings, this approach involves iterating through the string to reverse it and then comparing the original and reversed strings.