哪四種R

我猜是體表最外層形成花色的被毛+內層細絨毛+後腳跟像地毯一樣短短軟軟那層+鬚？

跟灰狐說的差不多！
我找到的網頁說：
Cats have four types of hair. There are short fluffy hairs called secondary hairs, underfur or undercoat. The second type is the longer and stiffer outer hairs called primary hairs, guard hairs, outer hairs, or outer coat. Cats, unlike some other mammals, also have hairs called awn hairs which are thinner than the primary hairs.

Finally, whiskers are actually specially developed hairs, called tactile hairs, which help the cat sense her surroundings.