As malaria is transmitted almost entirely by mosquito bites and mosqui

As malaria is transmitted almost entirely by mosquito bites and mosquitos are most active at night, the easiest and most cost-effective way to dramatically reduce the malaria rate in a country is to cover all beds and other sleeping areas with mosquito-proof netting. The World Bank ought, therefore, to reallocate substantial funds to purchasing mosquito nets for the areas most affected by malaria, which include Southern Continental Africa and the South American interior.

Which of the following is an assumption upon which the recommendation above depends?

(A) Exposure to malaria can have beneficial effects in some, particularly the very young.
(B) Malaria is the most serious disease that is transmitted by mosquitos.
(C) There exist no vaccines for malaria which are effective in all populations.
(D) World Bank efforts to reduce other diseases worldwide do not need the funds that would be reallocated.
(E) The rate of malaria infection is not substantially higher in Souther Continental Africa than in the South American interior.