- A night
- B noon
- C dawn only
- D never
Correct answer: A. night
Explanation: CAM plants (e.g. cacti) take in CO₂ at night, keeping stomata shut in the hot day.
Concept context
Light reactions, the Calvin cycle, C3/C4/CAM pathways, photorespiration, and factors affecting the rate of photosynthesis. One of the highest-yield NEET chapters.