Take a look at the official directions for Improving Paragraphs:
Each of the following passages is an early draft of an essay. Some
parts of the passages need to be rewritten.
Read each passage and answer the questions that follow.
Some questions are about particular sentences or parts of sentences
and ask you to improve sentence structure and word choice. Other
questions refer to parts of the essay or the entire essay and ask
you to consider organization and development. In making your decisions,
follow the conventions of standard written English. After you have
chosen your answer, fill in the corresponding oval on your answer
In plain English: some questions will ask you to deal
with fixing or combining individual sentences, and some will ask
you to deal with the essay as a whole.