All indicate that the universe is A) rotating.
B) expanding.
C) shrinking.
D) at equilibrium.

if its talking about earth then rotate I'll say

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

c, 1a hope this