I will try my best to sovle this question...
Im Pretty sure it has to be A. it needs to balance it would not stand in place if not balanced.
2H2+O2----->2H2O. I hope this helps
B. The limiting reactant determines the max amount of product that can be formed
True when the boron control rods are lowered it slows the reaction
A cold front is the leading edge of a cooler mass of air, replacing at ground level a warmer mass of air, which lies within a fairly sharp surface trough of low pressure.