—Heoughttohavebeenwarnedofthedanger. —

— He ought to have been warned of the danger.

— ______, but he just wouldn’t listen to me.

A. So ought he B. So he was

C. So was he D. So he had

選B。ought to have been warned of表示“本應該被告誡有危險”，是對過去動作的推測，因此回答也應該用過去時。A的構成形式不對。而So he was必須與第一句謂語動詞have been一致。