Answer:
The answer is the last one: D.
Explanation:
We know that one acre is equal to 0.0015625 square miles, so that would be the first part of the proportion. You are trying to find how many square miles are in 7 acres, so that would make 7 acres over x square miles. The proportion would now look like this: 1 acre over 0.0015625 sq. miles = 7 acres over x square miles. Cross multiply.
:D Hope this explains how to get the answer.