Which of the following groups of words is a sentence fragment?

A. When we stopped by the garden.

B. Stopping by the garden, we saw that the flowers were in bloom.

C. Stop by the garden.

D. We stopped; she didn't.

It's A. When we stopped by the garden. Had this question and got it correct.

The answer is A. This choice is a sentence fragment because it cannot stand alone as its own statement. All of the other choices are complete sentences in different ways. Answer "C" is a short directive that just tells someone to stop by the garden, answer "D" is a conjunction of two sentenced using a semi-colon, and answer "B" is a complete sentence is past-tense.