What's the middle layer of the ocean known as?

a. pycnocline
b. mesocline
c. mixed layer
d. deep ocean

I think it is 'A'

Explanation:

Because when mesocline is a really a known word. Also, when you search what it is. It is a different word. Mixed layer obviously doesn't make sense. And deep ocean most likely mean the trenches. But pycnocline is a layer in an ocean in which the density increases rapidly with depth. P.S. sorry if I'm wrong. This is the best I can give you.

the growth of the plants is affected by the heat of the light. what is the student doing?