Directions: In this question, a sentence has been given in Active/Passive form. Out of the four alternatives suggested, select the one which best expresses the same sentence in Active/Passive voice.

I can write a book on grammar.

Explanation for option 1: This is correct as per the rules of active/passive voice. Explanation for option 2: “could be” should be replaced by “can be” here. Explanation for option 3: This is incorrect as “can” in the “active voice” changes into “can be + past participle” in the passive voice. Explanation for option 4:  “Can” in the “active voice” changes into “can be + past participle” in the passive voice.