Ai Ling ______ to Manhattan in 1997.

Correct answer: was transferred

Explanation: Use the simple past passive for an action completed at a specific time in the past (for example, "in 1997").

• has been transferred: Present perfect passive, which is not used with a definite past time like "in 1997."

• should be transferred: Expresses advice or obligation, not a completed past event.

• was transferred: Simple past passive — appropriate for an action completed at a specific past time (correct).

• is transferred: Present simple passive, which suggests a present or habitual situation, not a one-time past event.