As a Rock Sinks Deeper and Deeper into Water of Constant

Multiple Choice

As a rock sinks deeper and deeper into water of constant density, what happens to the buoyant force on it if it started above the surface of the water?

A) The buoyant force remains constant.
B) The buoyant force steadily decreases.
C) The buoyant force first increases and then remains constant.
D) The buoyant force keeps increasing steadily.