The correct option is D CH4
Earth was formed approximately 4.5 billion years ago. As it cooled down, a primitive atmosphere was created by the outgassing of early volcanoes. The early atmosphere contained no oxygen and could not support most of the life forms. In addition to the molten lava flowing into the ocean, some of the chemicals viz., H2, CH4, NH3, CO2 and water vapourwere supposedly washed down by the rains into the ocean where these chemicals gradually converted to simple organic molecules that eventually joined together into complex organic molecules like DNA and RNA.