Answer:
A) The high temperatures denature the proteins in the plasma membrane, thus making many of the cells unable to function properly.
Step-by-step explanation:
Photosynthesis like other biochemical processes performs best in an ain optimum range of temperature. It is observed that, in the presence of sufficient carbon dioxide (CO₂) and light, the rate of photosynthesis increases with increase in temperatures up to the optimum level ( 20⁰C to 30⁰C). Increase in temperature beyond the optimum levels, the enzymes(proteins) become inactive or destroyed thus, stopping of photosynthetic reactions which are catalysed by enzymes.