In the African countries where HIV/AIDS is a big problem the economies have big problems. People that have it are usually young people, they lack the physical power and the concentration to be effective workers, or they can not work at all, and this affects the economy because the efficiency is very low or non existent from the people that have HIV/AIDS. Also, this means that this people need medical care, an expensive one, and they usually do not have the resources to pay for it, so the governments spend big amounts of money on this as well.
The main idea of this paragraph is A
Uniformitarianism- the theory that changes in the earths crust during geological history have resulted from the action of continuous and uniform processes
Measuring in light-years also allows astronomers to determine how far back in time they are viewing , Because light takes time to travel to our eyes. Everything we view during the dark in night has already been happened.