The primitive atmosphere was reducing in nature.
Free oxygen was absent in the primitive atmosphere.

Options

A. If both (A) and (R ) are true and (R ) is the correct explanation of (A).
B. If both (A) and (R ) are true but (R ) is not the correct explanation of (A).
C. If (A) is true but (R ) is false.
D. If both (A) and (R ) are false.

Answer

A