How Does the Concentration of Prokaryotic Cells at the Surface

Multiple Choice

How does the concentration of prokaryotic cells at the surface of pelagic water compare with the concentrations at depths below 1000 m?

A) There is a decrease in concentration from 1 m to 1000 m in depth, then a dramatic increase below 1000 m.
B) There is a decrease in concentration with increasing depth.
C) There is a steady increase in concentration with increasing depth.
D) There is an increase in concentration at depths below 1000 m.