Which of the following sentences is in the future perfect tense?

The correct answer is Option (3) → The teachers will have checked all the answer sheets by the end of May.

Future perfect tense:

• Its form is will have + past participle (V3).
• It shows an action that will be over by a future time.
• In Option 3, “will have checked” has “will have” and the V3 “checked”, and “by the end of May” is the future time.
• Example: By June, we will have shifted to the new flat.

Why the Other Options are Incorrect?

Option 1: The teachers will have to check all the answer sheets before the vacation. — Incorrect.

• This is the simple future of “have to”: will have to + base form.
• It shows a future duty.
• “Check” is the base form, not the V3, so this is not will have + V3.

Option 2: The teachers will be checking answer sheets all through the first week of May. — Incorrect.

• This is the future continuous: will be + V-ing.
• It has “will be checking”, not “will have” + V3.

Option 4: The teachers have checked only half of the answer sheets so far. — Incorrect.

• This is the present perfect: have + V3.
• It has no “will”, so it is not a future tense.