West Nile is carried by mosquitoes. Mosquitoes use bodies of water, such as ponds, to lay their eggs. If you live near a pond, there are going to be a lot of mosquitoes around you, thus making you more susceptible to West Nile.
The correct answer is - A sudden drop in sugar prices or in production caused by a natural disaster could cripple Cuba's economy.
Being heavily reliant on one product is always a very tricky situation for the economy of a country, and in the case of Cuba, the big reliance on sugar cane exports, can easily cripple the country's economy.
When the prices of the sugar drop, or there are natural disasters that destroyed big portion of the plants (which is common in the Caribbean region), the economy immediately suffers. All of the people in the country are affected, as big portion of them are working in that industry, so when they lack money, there's not enough money for circulation in the economy. That will result in bigger amount of money to be let in circulation, but that will result in high inflation.
Fossil fuels are not effected by acid rain.
what do you mean by "war and conflict in grapes"