Which of the following ecosystems would likely have a larger net primary productivity/hectare?

A) open ocean because of the total biomass of photosynthetic autotrophs
B) grassland because of the small standing crop biomass that results from consumption
by herbivores and rapid decomposition
C) tropical rainforest because of the massive standing crop biomass and species
diversity.
D) cave due to the lack of photosynthetic autotrophs
E) tundra because of the incredibly rapid period of growth during the summer season.