Question

Higher productivity has been achieved for some greenhouse crops such as tomatoes and bell pepper by

• A. increasing carbon dioxide concentration
• B. decreasing carbon dioxide concentration
• C. increasing oxygen concentration
• D. decreasing oxygen concentration

Answer 1

The correct option is A increasing carbon dioxide concentration

The $C_3$ and $C_4$ plants respond differently to $C{O}_2$ concentrations. At low light conditions neither group responds to high $C{O}_2$ conditions. At high light intensities, both $C_3$ and $C_4$ plants show an increase in the rates of photosynthesis.
Tomatoes and bell pepper are $C_3$ plants. Exposing them to carbon dioxide rich air will increase their productivity.