Why many dies of yellow fever in haitian revolution?

Causes of the Epidemic

Why did yellow fever decimate the French so thoroughly? First, the biological environment was ideal for a yellow fever epidemic. French had never been exposed to yellow fever. Therefore, they represented a virgin population for the disease and were predisposed to acquiring the disease. The indigenous people represented the reservoir for the disease, but were somewhat resistant to its effects because of repeated exposure. Finally, the yellow fever mosquito was plentiful in 1802 and 1803.

Second, the physical environment also was favorable for an epidemic. Spring rains provided ample mosquito breeding sites. Quagmires and swamps surrounded many of the port towns (such as Port-au-Prince). Further, the hot, humid conditions stressed the French from the moment they disembarked from the ships.

Third, as is common in war, the social environment was favorable for the outbreak of disease. As the insurgency progressed, most of the principal cities were burned. The French were unable to use the valuable resources that these towns could have provided: medical supplies, clothing, and shoes (Fick 1990). Napoleon prevented LeClerc from outposting in the mountains after his initial successes in controlling the port towns. Instead, the bulk of the army was stationed in the low lying regions of Haiti, where the mosquitoes were more onerous. It was long known that mortality from yellow fever and malaria in the Caribbean could be substantially reduced by moving troops to mountain camps (Buckley 1985). For strategic reasons, however, the troops needed to remain in the low lying port towns.  info from http://www.montana.edu/historybug/napoleon/yellow-fever-haiti.html

the answer would be c