The concentration of $CO_2$ in the atmosphere is $...............$ and if the concentration of $CO_2$ is increased up to $\ldots \ldots \ldots$,it can lead to an increase in the rate of $CO_2$ fixation.

• A
  $0.01$ to $0.02 \%, 0.05 \%$
• B
  $0.1$ to $0.2 \%, 0.05 \%$
• C
  $0.3$ to $0.4 \%, 0.5 \%$
• D
  $0.03$ to $0.04 \%, 0.05 \%$