Select the option that expresses the given sentence in active voice.
"He must be written to by us."

Correct option is B

Explanation of the Correct Answer: · The given sentence is in passive voice.
· Active voice structure: Subject + Modal Verb + Base Verb + Object.
· Passive form: Object + Modal Verb + be + Past Participle + by + Subject.
· The subject is "we," and the object is "him" (from "to him").
· The correct active sentence is: "We must write to him."
Why Are the Other Options Incorrect? · (a) "We can write." → Incorrect; it changes the modal verb "must" to "can," altering the meaning.
· (c) "We are writing to him." → Incorrect; it changes "must be written" (obligation) to present continuous.
· (d) "I have been writing to him." → Incorrect; it changes the sentence to present perfect continuous.
Thus, the correct sentence is:
"We must write to him."