For the chemical reaction $N_2 + 3H_2 \rightarrow 2NH_3$,the rate of reaction can be expressed in terms of the derivatives of the concentrations of $N_2$,$H_2$,or $NH_3$. Write the correct relationship between the rate expressions.

• A
  Rate $= -\frac{d[N_2]}{dt} = -\frac{1}{3}\frac{d[H_2]}{dt} = \frac{1}{2}\frac{d[NH_3]}{dt}$
• B
  Rate $= -\frac{d[N_2]}{dt} = -\frac{3d[H_2]}{dt} = \frac{2d[NH_3]}{dt}$
• C
  Rate $= \frac{d[N_2]}{dt} = \frac{1}{3}\frac{d[H_2]}{dt} = \frac{1}{2}\frac{d[NH_3]}{dt}$
• D
  Rate $= -\frac{d[N_2]}{dt} = -\frac{d[H_2]}{dt} = \frac{d[NH_3]}{dt}$