How do ${\mathrm{C}}_3$ plants respond to increased ${\mathrm{CO}}_2$ concentrations compared to ${\mathrm{C}}_4$ plants under optimum light intensity conditions?

${\mathrm{C}}_3$ plants respond to increased ${\mathrm{CO}}_2$ concentrations with increased photosynthesis rates and show  saturation beyond $450 \mu \mathrm{lL}-1$.

${\mathrm{C}}_3$ and ${\mathrm{C}}_4$ plants do not show any difference in response to ${\mathrm{CO}}_2$ concentration.

${\mathrm{C}}_3$ plants show decreased photosynthesis rates.

${\mathrm{C}}_3$ plants show saturation at lower ${\mathrm{CO}}_2$ concentrations than ${\mathrm{C}}_4$ plants