Removable media are useful for a classroom teacher because they

A) are read only.
B) cannot be erased accidentally.
C) have the greatest capacity of any storage device.
D) are portable.

I believe the answer is A, is this correct?

I would go with D. They are portable - think of a CD or an USB device. You can insert a CD or USB and take it out. If the teacher changes classes, she can take her removeable media with her.