Behavioral observation means measuring behavior as it occurs. In this it needs recording from the person then the patient.
In some cases natural observation is also done. Like if a patient is child then the observer will go the classroom and records the behavior.
Hence the option c is not correct.
Self-monitoring as the name indicates it is the self reporting of the behavior by the patient from time to time, how often problems are occurring, duration and the nature of the lifestyle.
Hence the option b is not correct.
Behavioral avoidance tests are often used to assess phobias and avoidance behavior by asking them to reach near to the feared situation.
Hence the correct option is .