Which of the following would happen if the supply of ${\mathrm{O}}_2$ is decreased to an illuminated wheat plant

Water stress in plants causes a decrease in photosynthesis because:-

(A) it reduces the CO₂ availability
(B) it reduces the surface area of the leaves
(C) it reduces the metabolic activities of leaves

Choose the correct option from the following:-

When two plants $\mathrm{L}$ and $\mathrm{M}$ were exposed to different light intensities and temperatures, they showed changes in their rates of photosynthesis, which have been represented in the following graph. 

The graph indicates that