Mencius Used Water as a Metaphor to Illustrate

Mencius used water as a metaphor to illustrate:

A) The destructive power of untrammeled emotions to flood one's life.
B) The impossibility of stepping into the same river twice.
C) The tendency of a person's nature to freeze in place, like a block of ice.
D) The importance of allowing behavior to flow naturally, and not be blocked by artificial constructions.