Refer to the Following Choices to Answer the Questions Below

Refer to the following choices to answer the questions below. Chose the answer that best describes the chemical composition of the object.
-the atmosphere of Mars

A) nickel and iron
B) 80 percent nitrogen, 20 percent oxygen
C) 95 percent carbon dioxide
D) mostly hydrogen and helium
E) frozen methane, ammonia, water, and other gases and dust