When a writer does not know who performed the action in a sentence the writer can still write a grammatically correct sentence by? a. using the active voice b. using the passive voice c. ending the sentence with an infinitive d. ending the sentence with a preposition

The answer to your question would be that 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 passive voice. That is, the correct option would be B.

It is not necessary for you to know the doer of the action (or agent) in order to write a grammatically correct sentence. If you don't have this information, you can change the normal word order of many active sentences (those with a direct object) so that the subject is no longer or active but acted upon the verb or passive.

im not entirely sure what you're asking.