Which of the Following Is Believed to Form Part of the Current

Multiple Choice

Which of the following is believed to form part of the current atmosphere of the Earth?

A) the remnants of the original hydrogen and helium gas from the solar nebula attracted by the protoplanet
B) the result of the melting and vaporizing of the glaciers from the last ice age
C) gases that were outgassed from the heated rocks sometime after the planet formed
D) hydrogen and helium from a collision between the Sun and another star