C, pretty sure due to natural selection and theory of evolution
Mortality, or death rate is a measure of the number of deaths in a particular population, scaled to the size of that population, per unit of the time. In this case a factor that would result to an increased mortality rate in a population due to increased competition of water will be the density-dependent factor.
Answer: Antibiotic Resistant Mutation
Explanation: Not all of the bacteria die because there are individuals in the population that have an antibiotic resistant mutation, which causes them to be adapted to dealing with the antibiotic. There will be a large population of bacteria again because the ones with the mutation survive, reproduce, and pass the antibiotic resistance trait on.
I would go with c because its tells you right in there that the ecosystem help who lives around that area.
