Answer:
Option: c is the correct answer.
c. After she finished writing her first novel.
Explanation:
Sentence fragment--
Sentence fragment are a group of words that look like they are sentences but actually are not.
They do not have any independent clause which is necessary for a complete sentence to have.
i.e. a complete sentence must have atleast one independent clause i.e. it could be stand alone.
Hence, from the given choices that best describes a sentence fragment is:
c. After she finished writing her first novel.
( Here these group of words do not make any sense for what it is trying to say)