The correct option is D has been adopted by Sam.
The correct answer is ‘has been adopted by Sam’. In passive voice, the receiver of the action appears first and since the receiver is singular, ‘A dog’, the singular form of the helping verb, ‘has’ is used. It is followed by the ‘be’ verb form ‘been’, the past participle form of the main verb ‘adopt’ which is ‘adopted’, the preposition ‘by’ and the doer of the action, ‘Sam.’