Answer: D) good sanitation and medical advances
In the exponential growth, the population's growth rate increases over time, in proportion to the size of the population. It causes the population to increase faster in numbers. Good sanitation and medical advances will contribute to the exponential growth of the human population because clean environment will prevent the accumulation of pathogen inside the body and hence will prevent the cause of diseases. Medical advances will help in curing of deadly diseases like cancer hence, will increase the likelihood of survival of more number of individuals.
