Select the option that expresses the given sentence in passive voice.

She has written many books.

Many books have been written by her.

The correct option that expresses the given sentence in passive voice is Many books have been written by her.

The other options are incorrect because:

• Many books were writing her is in the active voice.
• Many books were being written by her is in the present progressive tense, while the original sentence is in the simple past tense.
• Many book have written her is grammatically incorrect. The verb "to write" is transitive, which means that it takes a direct object. However, the subject of the sentence is "many books," which is not a direct object.