The ratio between N2 and the product is 1:2.
The ratio between H2 and the product is 3:2.
These ratios are deducted from the stoichiometry coefficients, which indicate the molar quantity of each molecule.
From these ratios, we can deduct the answer most contain greater moles for H2 than for N2 because the hydrogen molecule represents more product, this leaves us with two possible options: a and b.
At last, if we use 2 moles of N2 and 4 moles of H2, we would get the greatest amount of product, and we are using the proper ratio indicated by the chemical equation.
Therefore, the answer is a.