Use the Following Figure to Answer the Question

Use the following figure to answer the question.

What treatment results that were presumably part of the experimental design are not fully depicted in the graph?

A) Chlorophyll a concentration at 30 m depth within the treatment area
B) Chlorophyll a concentration at the surface within the treatment area
C) An indicator of net primary production in the treatment area at the surface and at 30 m deep
D) An indicator of net primary production outside the treatment area at depth and at 30 m deep