Option A
A. There is a patch of white hairs at the base of each ear.
B. The tail is longer than the head and body.
C. The tail has very fine hairs on it, making it hard to see the scales underneath and there may be longer hairs on the back half of the tail.D. The hind feet are very long.
Select

Option B
A. There is no patch of white hairs at the base of each ear (except in Mastomys pernanus).
B. The tail may or may not be longer than the head and body.
C. There are always scales or rings of scales visible somewhere on the tail and there may or may not be longer hairs on the back half of the tail.D. The hind feet are not exceptionally long.
Select