Hint:The plants which live in warm and dry environments have to adapt in order to reduce the excessive loss of water due to transpiration.
Complete answer: Warm and dry conditions of the environment are challenging for the plants. It becomes difficult for regular plants to survive in such situations due to excessive heat and loss of water due to transpiration. So, the plants adapt to such situations. These adaptations are necessary for the survival of the plants in those harsh environmental conditions.
Closure of stomata throughout the night is not an adaptation to dry climate because plants lose water through stomata in the day when the rate of transpiration is much higher due to the high temperature.
Photorespiration is a process that reduces the efficiency of RUBISCO and increases the demand for keeping stomata open for a longer time in order to carry out photosynthesis. This opening of stomata for a longer duration will lead to more loss of water through transpiration. The spatial separation of carbon dioxide fixation and RUBISCO activity in mesophyll cells and bundle sheath cells of C - 4 plants respectively is useful in avoiding photorespiration by concentrating the carbon dioxide in bundle sheath cells so that the oxygenase activity of RUBISCO is scaled-down and there is an increase in the RUBISCO efficiency. This increased RUBISCO efficiency allows higher rates of photosynthesis even when stomata are closed for a long time. It also reduces photorespiration and water loss.
CAM plants reduce water loss by opening their stomata at night only.
So, the correct answer is option A.
Note: Some examples of CAM plants are –
Maize, Sugarcane, and Sorghum
The CAM plants are very efficient in warm and dry climates. They make a lot of energy.