Anne has decided to write an article on the topic of uniforms. Her research question is “Why do people wear uniforms?” Here’s a paragraph from the first source she consults:

Uniforms have been worn throughout history for a variety of reasons. Police officers and guards wear uniforms to signify authority and power. Soldiers wear uniforms to identify their branch of the armed forces and show that they’re part of an organized group. Workers wear uniforms to show where they work, to protect them as they work, and to symbolize what they do. Members of sports teams wear uniforms to show they play for the same team, and to allow them to perform their sport well.

After reading this source, she decides to focus her research by asking a further question. Which of the following questions will help Anne focus her research?

A.
Do students like wearing school uniforms?
B.
Do sports teams ever change their uniforms?
C.
How many people in the United States wear a uniform to work?
D.
What are the reasons that different groups wear different types of uniforms?