Choose the correct adverb to fill in the blank:

He ran __________ in the race.

quickly

The correct answer is option (3) quickly.

An adverb is needed to describe how he ran in the race. "Quickly" is the appropriate adverb here as it describes the manner in which he ran, indicating that he ran with speed. Options (1), (3), and (4) are not adverbs and do not appropriately describe the manner of running.