You have been trying to add a specialized channel to an image for a few minutes and it does not seem to be working. Which of the following could be the problem?

You have never used channels before but you have heard colleagues tell you how useful they can be, so you decide to do some experimenting yourself.

a. You are trying to add it to a bitmap image.
b. You are trying to add it to a composite image.
c. You are trying to add it to a CMYK image.
d. Both a and c.

a. You are trying to add it to a bitmap image.