HELP ME I DON”T UNDERSTAND AND IT”S MULTIPLCE CHOICE PLZZZ

If a terrestrial ecosystem has a net primary production of 3000 J/m2 *yr and an Ra of 2000, what is the gross primary production for this ecosystem?

A. 100
B. 500
C. 1000
D. 5000

Consider darwin's first writings on the theory of natural selection. an important point of darwin's essay on the principle of population, written in 1798, was a peer's observation that in nature plants and animals produce far more offspring than can survive, this observation can be attributed to a) charles lyell. b) thomas malthus. c) jean-baptiste lamarck. d) johann friedrich meckel.

Each hereditary trait corresponds to

Can someone i have no idea of how to do this.