A suitable title for this passage might be（）

A．The sloth does not eat any meat
B．For most of its time, the sloth remains motionless on the ground
C．To some extent, the sloth is protected by the moss growing on its body
D．The sloth has a brown fur of its own

A．to help children to gain a better understanding of animal life
B．to prove that the saying "a rolling stone gathers no moss" is wrong
C．to introduce a particular animal to the common reader
D．to discuss with professionals the laziness of animals