Load testing is not a type of functional testing; instead, it falls under non-functional testing. Functional testing focuses on verifying the functions and features of the software application according to the specified requirements, while non-functional testing assesses aspects like performance, scalability, and reliability. Load testing specifically evaluates the system's behavior under expected and peak load conditions.

Katalon Studio's "Data Binding" feature facilitates easy implementation of data-driven testing. Testers can link test data sets to test cases, allowing for multiple iterations with different input values. This streamlines the testing process, enhances coverage, and ensures comprehensive validation of the application under various scenarios.

Independence is a fundamental principle of functional testing, emphasizing the need for testing to be carried out impartially from the development team.

A Use Case Diagram is a graphical representation of the interactions between users (actors) and a system, illustrating how the system responds to external stimuli. It provides a high-level view of the system's functionality and the actors involved in various use cases.

Environment variables in Postman allow testers to store and manage dynamic data, facilitating the creation of flexible and reusable test scenarios. By using environment variables, testers can efficiently handle dynamic elements such as URLs, tokens, or parameters, enhancing the flexibility and maintainability of API tests.

Selenium Grid offers benefits in a testing environment by enabling parallel test execution across multiple machines, supporting cross-browser testing on various configurations, facilitating distributed testing by distributing test cases, and optimizing resources by utilizing available machines efficiently. It enhances test scalability and reduces execution time, making it a valuable tool for large-scale testing projects.

Load Testing is specifically designed to evaluate how well the system performs under expected loads, ensuring it meets performance requirements.

The Risk Mitigation approach in testing involves proactively setting aside resources to address potential risks. It aims to reduce the impact or likelihood of risks and ensure that testing activities proceed smoothly even in the presence of uncertainties.

Load testing evaluates how the system performs under varying network conditions and assesses its responsiveness and reliability in real-world scenarios.

Decision Table Testing is the most suitable technique for testing complex business rules, like those involved in discount calculation logic. It allows testing various combinations of conditions and their outcomes, ensuring thorough validation of the billing system's logic.