<span>C.The amount of light </span>
Answer:
Individuals in a population are naturally variable, meaning that they are all different in some ways. This variation means that some individuals have traits better suited to the environment than others. ... Through this process of natural selection, favorable traits are transmitted through generations.
Other reasons are
Not finishing the antibiotics.
Or
Taking antibiotics too often
I'm not too sure which one of these two but its either A or C
