Subtraction of which of the following will convert gross primary ...

[penza]

Subtraction of which of the following will convert gross primary productivity into net primary productivity?
A) the energy contained in the standing crop
B) the energy used by heterotrophs in respiration
C) the energy used by autotrophs in respiration
D) the energy fixed by photosynthesis
E) all solar energy

[plus1]

I recall doing this last year, it's C, bye bye!

[penza]

Thanks for assisting, your answer was right!