If You Were on a Ship and Observed Bioluminescence in the Ocean

If you were on a ship and observed bioluminescence in the ocean, what is the most logical conclusion you could draw about the surrounding waters?

A) Phytoplankton are present at low densities, allowing for proliferation of bioluminescent bacteria.
B) Vibrio bacteria are present in small numbers, unable to compete with phytoplankton for nutrients.
C) Phytoplankton are using bioluminescence to attract fish-a natural predator of bacteria.
D) Both Vibrio bacteria and phytoplankton are present at high densities.
E) Phytoplankton are producing bioluminescence to attract bacteria.