Answer:
A (the first answer)
Explanation:
The main idea of this paragraph is that the students attending schools with mandatory uniform policies experience less pressure than do students who
must choose their wardrobes. So, the author is FOR mandatory uniform policies
With this information, we want evidence that supports the main idea.
Option B is just a statement that explains how if parents want to exempt their children from uniforms, they need to talk to the administration.
Option C is just a statistic that states the number of students that had uniforms.
And Option D is, again, just a statement that doesn't support the main idea.
So the correct answer is A.