what does primary productivity measure? how producers carry out photosynthesis the rate at which phototrophs make organic matter the number of consumers that make up a food web how energy moves from organism to organism

The correct answer would be the rate at which phototrophs make organic matter.

Explanation:

The rate at which all the phototrophs that are photosynthetic organisms and plants produce the organic compounds or matter in an ecosystem called primary productivity measure.

Gross productivity and net productivity are the 2 aspects of primary productivity.

Gross productivity is the total production of organic matter by phototrophs in an ecosystem.

Net productivity is the organic materials that left after phototrophs in the ecosystem have utilized some of these organic compounds for their cellular energy functions.

Thus, the correct answer is the rate at which phototrophs make organic matter.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.