Which is a sentence fragment? a. to do whatever he wants them to do. b. the sound of footsteps frightened us. c. then it was over before we knew it. d. baby birds hatched in the tree in the backyard

A. To do whatever he wants them to do.

A sentence fragment is a sentence that is incomplete, one that is separated from the main claus. In this case "To" is a preposition, which means that there should be more to the sentence. You can tell because you can't fully understand the idea behind the sentence. Therefore A, is the fragment.

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