In the Client-Server architecture, services communicate via a well-defined interface using lightweight protocols. This architectural style is characterized by the separation of client and server roles, where clients request services from servers, which can be located on different machines or networks.

Readability is a software quality metric that assesses the simplicity and clarity of the code in a software project. It focuses on how easy it is for humans to read and understand the code. Clear and simple code is essential for maintainability and collaboration among team members.

Configuration Control in SCM is responsible for managing changes to documents, codes, and other entities during the software development process. It includes processes for submitting, reviewing, approving, and implementing changes.

Prioritizing test cases is essential to save time and effort. It allows testers to focus on critical and high-priority test cases first, ensuring that important areas of the software are thoroughly tested. This approach helps in early defect detection and efficient resource utilization.

Reliability is the quality attribute that pertains to a system's ability to function correctly even when faced with invalid inputs or stressful environmental conditions. In software engineering, reliability is crucial for ensuring consistent and dependable performance.

Software Quality Assurance (SQA) contributes to improved communication by providing project documentation, which includes guidelines, standards, and processes. This documentation helps team members understand their roles, responsibilities, and the expected quality standards for the project.

System testing focuses on validating the entire software system, ensuring that it meets the specified requirements and functions as intended. This includes verifying the software architecture, interfaces, and overall functionality.

In this scenario, the issue is related to validation. Verification ensures that the software is built as per the specified requirements, while validation ensures it fulfills user needs. The problem arises because the software may meet its documented requirements but not satisfy what users truly need in the real world. This highlights the importance of both verification and validation in the software development process.

A primary key in a database table is used to uniquely identify each row in the table. It ensures that no two rows have the same values for the primary key, making it a crucial concept for data integrity and efficient data retrieval.

Black Box Testing is called so because it symbolizes testing without any knowledge of the software's internal structure, just like a tester is working with a "black box" and doesn't need to see what's inside. This approach emphasizes testing solely based on external behavior.

The primary purpose of the Observer design pattern is to maintain a one-to-many dependency between objects. This means when one object (the subject) changes its state, all its dependents (observers) are notified and updated automatically. It's commonly used in scenarios where you need to implement distributed event-handling systems or maintain consistent data across multiple objects.

Build Management in SCM contributes by automating the process of building software components. It ensures that the right code and dependencies are compiled, integrated, and packaged correctly, enhancing the consistency and reliability of the build process.