Which below would be considered covert surveillance?

Covert surveillance refers to monitoring or observing individuals or locations without them being aware that they are being observed. This approach aims to gather information discreetly to ensure that the subject's behavior is not influenced by the knowledge of being watched, which can significantly affect the validity of the data collected.

Conducting surveillance from a place hidden from view exemplifies this concept perfectly. It allows the observer to capture genuine actions and interactions of the individual or group being surveilled. Such tactics are often used in investigations, intelligence gathering, and security assessments to obtain accurate and unbiased information about a subject's activities.

In contrast, openly following someone or sitting outside a house in plain view does not fit the criteria for covert surveillance because the subjects are aware of the observer's presence. This awareness can lead to altered behaviors, making the gathered information less reliable. Thus, the elements of secrecy and discretion are what define covert surveillance, which is why the first option is the correct choice in this context.