Which of the following is an example of exigent circumstances?

Exigent circumstances refer to situations where law enforcement officers can act without a warrant due to an immediate need to prevent harm, the destruction of evidence, or a suspect's escape. The scenario of an officer smelling drugs from a vehicle exemplifies exigent circumstances because it suggests that there is an immediate potential for evidence to be lost or destroyed if the officer does not take action quickly. The smell indicates that illegal activity may be occurring, and the officer could reasonably believe that the situation requires prompt intervention to secure evidence or ensure public safety.

In contrast, the other options do not present the same level of urgency or imminent threat that would justify action without a warrant. A minor traffic violation typically does not meet the criteria for exigent circumstances because it does not pose an immediate risk that would necessitate immediate action by the officer. Requesting a warrant before entering a home indicates a cautionary approach that is generally required, except in exigent circumstances. Lastly, waiting for a suspect to leave a building does not demonstrate an immediate need for action and allows time for law enforcement to obtain the necessary warrants or permissions.