Although many people would not believe it, the mosquito is actually the most dangerous animal in Africa. While the bite of the black mamba is invariably lethal when untreated, this dreaded snake kills only a few dozen people per year. Hippopotami, with their immense strength and foul dispositions, kill hundreds of people per year in rivers and lakes, but the mosquito is still more dangerous. Mosquitoes bite hundreds of millions of people in Africa every year, and they infect over a million each year with malaria, a disease that is often fatal. Which of the following questions would be most useful in evaluating the claim made above regarding the mosquito?