What is the result of starting a Diagnostic Session?

According to the Diagnostic Sessions document1, a diagnostic session is a timed session in which AppDynamics captures transaction snapshots for a business transaction at a more frequent interval that you set. In the session, AppDynamics captures full call graphs for the transactions. A diagnostic session can be triggered manually or automatically based on a health rule violation or a threshold of slow or error transactions. A diagnostic session is always associated with a specific business transaction, not all business transactions configured. Therefore, the correct answer is B. References:

Diagnostic Sessions