According to one of the most widely accepted theories the earth's atmosphere, before any life had originated on this planet, consisted of a mixture of [CPMT 1981, 84, 2002]

• A.            Water vapours, \[{{H}_{2}},N{{H}_{3}}\] and \[C{{H}_{4}}\]
• B.            \[{{H}_{2}},C{{O}_{2}},N{{H}_{3}}\]and \[C{{H}_{4}}\]
• C.            \[{{O}_{2}},N{{H}_{3}},C{{H}_{4}}\] and water vapours
• D.            Ozone, \[C{{H}_{4}},{{O}_{2}}\] and water vapours