Why is net primary production (NPP) a more useful measurement to an ecosystem ecologist than gross primary production (GPP)? A) NPP can be expressed in energy/unit of area/unit of time. B) NPP can be expressed in terms of carbon fixed by photosynthesis for an entire ecosystem. C) NPP represents the stored chemical energy that is available to consumers in the ecosystem. D) NPP is the same as the standing crop. E) NPP shows the rate at which the standing crop is utilized by consumers.