Which of the following sentences is in the passive voice?

The sentence "The new policy was approved by the committee" is in the passive voice because the subject (the new policy) is acted upon by the verb (was approved) rather than performing the action itself. In passive constructions, the focus shifts from the doer of the action to the receiver of the action. Here, the committee is the agent performing the action, but the sentence prioritizes the new policy, which is the object being approved.

In contrast, the other sentences emphasize the subjects performing the actions: the committee approving, the team winning, and the author writing. These sentences clearly indicate who is executing the actions, characteristic of the active voice. Thus, option B distinctly exemplifies passive voice.