Which of the following equations is correct regarding the rate of disappearance of reactant and appearance of product for the reaction $N_{2(g)} + 3H_{2(g)} \rightarrow 2NH_{3(g)}$?

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