What gas was lacking from earth's early atmosphere in the early precambrian era?

To relate to humans in a relational humanly way. 

This type of energy is called radiant energy.

Explosive eruptions are the most hazardous, involving large volumes of tephra and gases emitted from the volcano. lahars, pyroclastic flows, ashfall, and many other volcanic hazards are commonly associated with explosive eruptions. explosive eruptions are very dangerous. basically, any form of hazard can occur.

Ithink it's d. changemodify means to change.hope it ! : )