Which Statement About the Black Sea Is False

Which statement about the Black Sea is false?

A) Its waters are well oxygenated from the surface to the floor of the sea.
B) Because it is nearly land-locked, it exchanges little of its water with other ocean waters.
C) Native predators and parasites failed to regulate its sea comb population.
D) The state of its ecosystem improved between the early 1990s and the late 1990s.