Final answer:
The purpose of surveillance encompasses gathering evidence, monitoring individual's actions, and identifying associates, and it can be applied in multiple fields including law enforcement, foreign policy, and sociology.
Step-by-step explanation:
The purpose of surveillance is to: D. All of the above. This includes gathering evidence, observing an individual's actions, and identifying associates. Surveillance can be used in a variety of contexts including law enforcement, military operations, corporate security, and wildlife management. For example, in the context of U.S. foreign policy, it may serve the goal of keeping the country safe by monitoring potential threats. In the context of sociology, surveillance may be used to monitor collective actions, which can be less severe in small groups due to increased peer pressure and the ability to monitor individual behavior more closely. Additionally, surveillance techniques such as participant observation are used in research to analyze social behaviors and patterns.