For a zero order reaction $A \rightarrow \text{product}$,a plot of $[A]$ (on $y$-axis) and time (on $x$-axis) gave a straight line with slope equal to $-3 \times 10^{-3} \ M \ min^{-1}$ and intercept equal to $2 \times 10^{-2} \ M$ (on $y$-axis). What is the rate constant (in $M \ min^{-1}$) of this reaction?

• A
  $3 \times 10^{-3}$
• B
  $5 \times 10^{-5}$
• C
  $3 \times 10^{-4}$
• D
  $5 \times 10^{-4}$