Answer: a. Stomata open at Night
Step-by-step explanation:
As a tactic to minimize photorespiration in warm regions, many water-storing plants such as cacti and pineapples modified its method of carbon fixation. This process is called Crassulacean Acid Metabolism (CAM), following the plant family Crassulaceae, in which it was first identified. In these plants, the stomata (singular, stoma), specialized openings in the leaves of all plants through which CO2 enters and water vapor is lost, open during the night and close during the day. This model of stomatal opening and closing is the opposite of that in most plants.