Alexander Oparin and John Haldane Postulated That the Early Atmosphere

Alexander Oparin and John Haldane postulated that the early atmosphere was a reducing atmosphere. Why was this prediction an important one?

A) because the molecules contain the maximum possible number of protons that can be easily donated in reactions that lead to synthesis of complex molecules
B) because the molecules contain the minimum possible number of electrons that can be easily donated in reactions that lead to synthesis of complex molecules
C) because the molecules contain the maximum possible number of protons that can be easily accepted in reactions that lead to synthesis of complex molecules
D) because the molecules contain the maximum possible number of electrons that can be easily donated in reactions that lead to synthesis of complex molecules