The likelihood of having radon gas in your home depends largely upon the geology and soil types in your region. according to the epa,
a. toxic air pollutants are generally much more concentrated indoors than outdoors.
b. one of the reasons indoor air pollutants are so dangerous is the high amount of time people are indoors.
c. in the less-developed countries of africa, asia, and latin america, there is less indoor air pollution than in developed countries.
d. all of these statements are true.

d. All of these statements are true.

Explanation:

According to the "A Citizen's Guide to Radon" manual on the third page:

"Radon comes from the natural (radioactive) breakdown of uranium in soil, rock  and water and gets into the air you breathe. Radon can be found all over the U.S.  It can get into any type of building—homes, offices, and schools—and result in a  high indoor radon level. But you and your family are most likely to get your greatest exposure at home, where you spend most of your time."

According to a study by Brazilian researchers, the greatest exposure to gas radon occurs indoors, such as tunnels, wineries, mines and homes. All of these environments are typical of developed countries that exploit environments to build cities and homes for the population.

the sphincter muscles at the end of the digestive tract is the anus.

it marks things for degradation via the proteasome. it alters there celluar location.