What is the key difference between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP)? Group of answer choices A. GPP measures the energy captured and stored in plant biomass, while NPP measures the energy lost during plant respiration. B. GPP only accounts for energy used in maintenance, while NPP includes energy used for reproduction and growth. C. GPP is the energy converted into producer biomass, while NPP is the total energy captured by producers. D. GPP is the total energy captured and assimilated by producers, while NPP is the energy remaining after subtracting the energy used for plant respiration