Robin and Alex are discussing how water molecules form when hydrogen and oxygen atoms combine. Robin writes the following chemical equation to explain the formation of water.

However, Alex has a different opinion and suggests that the chemical reaction can be better represented by using the equation below.

Why does Alex’s equation better represent the reaction?
A.
For every two molecules of water formed, two hydrogen atoms are needed.
B.
The number of oxygen atoms is the same before and after the reaction.
C.
The amount of product formed should be more than the amount of reactants involved.
D.
For every two molecules of water formed, one hydrogen atom is needed.