Which colorless and odorless gas, produced by radioactive decay of uranium-238, is considered to be a form of pollution

Radon is the answer
 b

The troposphere gets warmer as altitude increases.

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey