What Is the Difference Between Elevation and Altitude

What is the difference between elevation and altitude?

A) Elevation is the height of a point on the surface of Earth; altitude is the height above the surface of Earth.
B) Elevation is the height above Earth's surface; altitude is the height of a point on Earth's surface.
C) Both refer to the height above the surface of Earth.
D) Both refer to the height of a point on the surface of Earth.