Q. He has been swimming . . . . . . . . one hour?
✅ Correct Answer: (D)
for
Explanation: 'For' can be used to indicate a duration, limit or an ending. Here, 'an hour' is a duration. Hence it makes the sentence meaningful.
Explanation by: Team MCQ Buddy
'For' can be used to indicate a duration, limit or an ending. Here, 'an hour' is a duration. Hence it makes the sentence meaningful.