I'd say A, myself. A has the most common head color and the most common "tail" color. Thus, it would probably be considered the most "normal."

Pretty messed up question, though.

While it is true that C is "abnormal", since it has two tails, BOTH of the tails are red, which would imply that that's the "normal" color, as it would be very ABNORMAL if it had not only two tails instead of one, but an abnormal color for both of them.