What kind of surveillance would you be conducting if you're monitoring a truck filled with computers while dressed in plain clothes?

In this situation, monitoring a truck filled with computers while dressed in plain clothes qualifies as covert surveillance. Covert surveillance typically involves observing a subject without their knowledge or consent, often to gather information discreetly and unobtrusively. The use of plain clothes is a tactic to avoid detection, indicating an intention to maintain a low profile.

Overt surveillance would imply that the subjects are aware they are being monitored, which is not the case here if the goal is to observe without revealing the surveillance itself.

Tandem surveillance refers to coordinated observation by two or more individuals, which does not apply in this context if only one person is monitoring the truck alone or without apparent cooperation. Therefore, this reinforces the conclusion that the correct choice reflects the nature of the surveillance being conducted in this scenario.