Biotic: " Produced or caused by living organisms" (definition excerpted from link below)
Since the temp., sunlight and precipitation are not produced or caused by living organisms, they cannot be the answer, since they are abiotic.
Since food is created by living organisms, food must be the answer. As a matter of fact, food is a huge factor in the growth of a population of anything, from bacteria to baleen whales and certainly humans.
Mineralogists group minerals into families based on their chemical composition. ... Most minerals are made up of combinations of chemical elements. In this group a single element like the copper shown here are found in a naturally pure form. Silicates This is the largest group of minerals.
The correct answer is stem cell research and animal testing.