The correct option is JSON. RESTful APIs primarily use JSON (JavaScript Object Notation) for data format due to its lightweight and easy-to-read structure. Unlike SOAP, which commonly employs XML, JSON is more concise and suitable for web-based communication.

Developers can assist testers by providing clear documentation for their code. Clear documentation helps testers understand the expected behavior, making it easier to create effective test cases. Writing complex and unreadable code, avoiding communication with testers, or skipping unit testing can hinder the testing process and lead to suboptimal results.

In data-driven testing, parameterization is crucial for handling diverse input values. It allows for a comprehensive coverage of scenarios, ensuring the API can handle a wide range of user data inputs. Randomly selecting test data may not provide systematic coverage, and prioritizing positive test cases alone might miss potential issues with negative scenarios. Unit testing is essential but doesn't address the need for handling diverse user inputs in the API.

Mock APIs with dynamic responses allow testers to simulate various scenarios, enabling comprehensive testing. Dynamic responses mimic real-world situations, making it a valuable tool in ensuring that the application behaves as expected under different conditions.

The primary goal of designing automation scripts for APIs is to automate repetitive tasks. This includes tasks such as sending requests, validating responses, and performing various checks, which ultimately helps in saving time and improving efficiency in the testing process. Automation also allows for the execution of a large number of test cases, facilitating thorough testing of API functionalities.

Rate limiting involves using a Token Bucket algorithm where tokens are added at a fixed rate, allowing for a smooth distribution of API requests.

Positive test cases verify the expected behavior of the API, while negative test cases focus on uncovering flaws or vulnerabilities in the API under adverse conditions.

The HTTP method GET is considered safe because it should not alter the state of the resource. It is used for retrieving information from the server without causing any side effects. Unlike POST or DELETE, which can modify or delete data, a GET request is supposed to be idempotent and should not change the state of the server.

Managing versioning in third-party API integrations involves including the version number in the request headers. This allows for smooth transitions between versions and ensures compatibility with the desired API functionality.

"Stubbing" tools are commonly used in API testing to emulate the behavior of third-party services. Stubs allow developers to define specific responses from API endpoints, enabling thorough testing of the application's interaction with external services.