Answer:
A) When the puppy first arrived at the Wilson's home.
Step-by-step explanation:
Sentence fragments can be a little tricky. They are basically, as the name suggests, a sentence-like structures that can't stand on their own and they don't convey complete information.
So, this means that sentence fragments are dependent clauses and phrases.
All of the answers are sentences (they have subject, verb, carry a full meaning) except for answer A.
That is a dependent clause because it tells us when something happened but we don't know what happened, thus, this is only a fragment that doesn't give us full information.