Question

when a writer does not know who performed the action in a sentence, the writer can still write a grammatically correct sentence by
using the active voice.
using the passive voice.
ending the sentence with an infinitive.
ending the sentence with a preposition.

Explanation:

Active voice requires a clear subject performing the action, which is unknown here. Passive voice shifts focus to the action or recipient, allowing the doer to be omitted or added later (e.g., "The window was broken" instead of "Someone broke the window"). Ending with an infinitive or preposition does not address the missing doer for grammatical correctness in this context.

Answer:

B. using the passive voice.