In Nitrogen fixation $N_2\qquad\underrightarrow {Nitrogenase}\qquad x \rightarrow NO_2^-\qquad\underrightarrow{\text{In soil}}\qquad y.$.The x in the equation is

Question

$\begin{array}{1 1}(a)\;NH_2\\(b)\;NH_3\\(c)\;N_2\\(d)\;NO_3\end{array}$