Which of the following actions is appropriate when encountering a plainclothes officer while on patrol?

When encountering a plainclothes officer while on patrol, exchanging identification discreetly is appropriate because it helps to maintain professionalism and ensures safety for both the officers involved. Plainclothes officers may be involved in sensitive operations, and identifying oneself respectfully can facilitate effective communication without alarming the public or compromising the mission at hand.

This approach emphasizes the need for cooperation between uniformed officers and their plainclothes counterparts, allowing for a unified response if necessary. It also shows awareness of protocols that are essential in maintaining the integrity of law enforcement operations, fostering a spirit of teamwork and mutual respect among officers, regardless of their uniforms.

The other actions are not ideal as they could lead to misunderstandings or create unnecessary tension in the situation.