8. What quantities are needed to describe the position of a water fountain relative to where you are standing?

D. the distance and direction to the water fountain

Explanation:

To describe the position of a water fountain relative to where one is standing, the distance and direction to the water fountain must be known.

This quantity is known as the displacement.

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.