Question

Small terrestrial bodies lacked gravity force which depends on mass to keep initial atmosphere supplied by its parental protoplanetary disk. Next, slow leakage caused by the sun's heat would ultimately deplete the primary atmosphere of small bodies. A second result may also have played a fundamental role in driving away the primary atmosphere.

Choose one-

a. slow leakage in upper atmosphere caused by the sun's wind

b. chemical reactions of atmosphere gas with rocks leading to a slow depletion of primary gases 

c. cooling down of opening atmosphere gas initiated internal chemical reactions producing liquid and solid minerals, that rain down to form oceans and the dirt we walk on

d. impact of large planetesimals would have blasted away substantial amounts of the body's primary atmosphere.