If You Rub the Scaled Skin of a Shark, It

If you rub the scaled skin of a shark, it feels rough if you move your hand from tail to head but smooth if you move from head to tail.What is a major advantage of the scales being oriented this way?

A) to keep the shark afloat in the water
B) to counteract friction as the shark swims through the water
C) to better protect the shark from predators
D) to better prevent water loss from the body tissues