He tried to push in, but he was sent . . . . . . . . back of the queue. A. at B. in C. about D. of

The correct answer is D. of.

The word “of” is used to indicate a position at the end of a series or sequence. In this case, the man was sent to the end of the queue.

The other options are not correct because they

• The word “at” is used to indicate a position in a particular place. In this case, the man was not sent to a particular place, but to the end of the queue.
• The word “in” is used to indicate a position inside something. In this case, the man was not sent inside the queue, but to the end of it.
• The word “about” is used to indicate a position near something. In this case, the man was not sent near the queue, but to the end of it.

Therefore, the correct answer is D. of.