The Water in a Deep Crater in a Bay on a Tropical

The water in a deep crater in a bay on a tropical island is a striking pure blue color.The water in the surrounding ocean is more of a green color.Which of the following is a logical hypothesis?

A) The water in the bay has a low level of phytoplankton and primary productivity, while there is a higher concentration of phytoplankton in the surrounding ocean.
B) The water in the bay has a high level of phytoplankton and primary productivity, while there is a lower concentration of phytoplankton in the surrounding ocean.
C) The concentration of phytoplankton and primary productivity in the bay and the surrounding ocean is the same, and it is very high.
D) The concentration of phytoplankton and primary productivity in the bay and the surrounding ocean is the same and is almost zero.