Stress testing is a dynamic testing technique used to determine how a software system behaves under conditions that are not normal or expected, such as under extreme loads, limited memory, or when subjected to hacking attempts. Its main goal is to ensure the software doesn't crash in suboptimal conditions.

The main purpose of static analysis in software testing is to identify defects in the early stages without having to actually execute the code. This is beneficial as it helps in improving the quality of the code and reduces the cost of fixing defects at later stages.

The prototype of a function includes the function's name, return type, and the types of its parameters. It provides a declaration of the function's signature, allowing the compiler to check function calls for correctness.

The freopen() function in C is used to redirect standard streams, such as stderr, to a specified file, enabling error messages to be stored in a file instead of the console.

To open a file for both reading and writing in C, you should use the "r+" mode with the fopen function. This mode allows you to perform both read and write operations on the file.

In C, the 'printf()' function is used to display output on the console.

The fopen function in C is used to open a file for reading. It returns a file pointer that can be used to read data from the file.

The correct answer is B) switch. The switch statement is ideal for situations where you want to execute different code blocks based on the value of a variable (in this case, the day of the week).

The correct option is 1. Using a struct with three integer fields is the most efficient way to represent a pixel in C because it encapsulates the RGB values as a single unit, making it easy to work with. The other options would be less efficient and less organized.

Usability testing is geared towards understanding how end-users interact with the software and ensuring a positive user experience. The primary considerations involve the system's ease of use, its consistency in design and functionality, and adherence to user interface design guidelines. UAT, on the other hand, determines if the system meets user needs, while load and compatibility have different focuses.

The "Defect Age" metric is a measure of the time between when a defect is introduced into the system and when it's discovered and resolved. It provides insight into how quickly a team identifies and addresses defects. MTBF (Mean Time Between Failures) measures the expected time between two successive failures of a system.

The "Record and Playback" technique involves recording user actions as they interact with the application. The recorded actions then form a script, which can be played back later. This technique is helpful for novice testers as it requires minimal scripting knowledge but is not always scalable.