plural forms - All of them are wearing an orange shirt. OR All of them are wearing orange shirts

Let's say there're three boys, and they all are in an orange shirt. Then, which one is correct?

A. All of them are wearing an orange shirt.

B. All of them are wearing orange shirts.

Of course, each of them is wearing ONE orange shirt, but because all of them are in a orange shirt, there're three orange shirts. So I'm confused.

Answer

Here is an example of single v.s. plural:

All of them are wearing orange shirts.

v.s.

Each of them is wearing an orange shirt.

This is because the first sentence refers to multiple shirts (on multiple people) and the second sentence refers to the single shirt worn by each member of a group of people.