Which factor is used to determine whether two organisms are members of
the same species?

According to the biological species concept, organisms belong to the same species if they can interbreed to produce viable, fertile offspring. Species are separated from one another by prezygotic and postzygotic barriers, which prevent mating or the production of viable, fertile offspring.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

i need an image of the diagram