The Evolutionary model of software evolution focuses on making the software adaptable without altering its core functions. This approach often involves iterative development and incremental updates to enhance the software's functionality while maintaining its core features. It is a popular choice for software systems that need to evolve over time to meet changing requirements.

The Single Responsibility Principle (SRP) states that a function or module should have one and only one reason to change, which means it should perform one specific job or responsibility. This helps in making the code more maintainable and understandable.

Corrective maintenance is about fixing errors or defects in the software. It addresses issues that may have been discovered during testing or reported by users and aims to restore the software's functionality.

The primary objective of conducting a software audit is to ensure compliance with established processes and standards. Software audits help identify deviations from best practices and ensure that the software development process is in line with defined guidelines and standards. It's a critical aspect of quality assurance.

Quality Assurance in the Waterfall model is often considered rigid due to its linear and phase-dependent approach. In Waterfall, each phase must be completed before moving to the next, making it inflexible for changes or adaptations after each phase begins.

The primary objective of software maintenance is to correct defects in the software. This includes identifying and fixing bugs, errors, and issues that may have arisen after the software's initial release.

The "Horizontal" prototype is employed to explore areas of the system with high technical risk. It focuses on integrating different system components to test their interactions. This type of prototype helps identify and address technical challenges.

The primary purpose of conducting stress testing is to assess how a software system performs under extreme conditions, such as high load or resource constraints. It helps identify system bottlenecks and performance issues.

In a healthcare system, where reliability and safety are paramount, verification ensures that the software complies with its documented requirements, and validation ensures that it functions safely in the real-world healthcare environment. The combination of verification and validation is crucial for preventing software errors, enhancing safety, and meeting regulatory and user requirements, all of which are essential in a critical healthcare system.

White box testing primarily focuses on the internal code structure, ensuring that the internal operations of the software perform correctly. It checks the correctness of individual code segments and their interaction within the application.

In a Waterfall model, frequent changes in project scope can pose significant challenges to Quality Assurance. Since the requirements are expected to be well-defined upfront, any scope changes can lead to discrepancies between what was initially planned and what is being delivered, making it difficult to maintain quality standards.

"Path" testing, a type of white box testing, ensures that every path in the code is executed at least once. It aims to cover all possible execution paths through the code to find potential issues.