Much of the Water on Earth,Venus,and Mars Has Come from Outgassing

Multiple Choice

Much of the water on Earth,Venus,and Mars has come from outgassing of water vapor from volcanoes.Much of the remainder is believed to have come from

A) chemical reactions,which have produced water from more complex molecules.
B) the combination of elemental hydrogen and oxygen in the atmosphere,the reaction powered by high-energy ultraviolet rays.
C) baking of rocks containing water.
D) the impacts of comets.