C. 6.81x10^-4
It is negative 4 because the 6 is 4 digits away from the first 0.
Scientific notation has one number and then the decimal place so it can not be A or E.
The correct answer is World's Worst Air Quality. These cities has the worst air quality in the world, since these two cities suffer from air pollution due to the overuse of cars, the exhaust of cars expels a lot of smoke that forms within the air that causes bad quality and increases particulates in the air, which results to respiratory illnesses among the citizens of the said countries/states. <span />
Nigeria is very hot, if you see pictures of Nigeria you can see how the sun is shining very brightly on the houses and on people. Their color of their skin are adapted to support the sun hot temperature.
