Explanation:

- Deserts: In deserts, many plants use Crassulacean Acid Metabolism (CAM) photosynthesis. They take up carbon dioxide at night to minimize water loss since desert conditions are hot and dry during the day. Correct Answer.

- Hilly terrains: Plants in hilly terrains typically follow C3 or C4 photosynthesis, which mostly happens during the day. They don't take up carbon dioxide at night generally.

- Roof tops: Roof top plants don't have a specific type of photosynthesis. Their CO2 uptake depends on the species, not the location itself.

- Ocean beds: Plants here refer to algae and seaweeds, which mostly perform photosynthesis during the day when light is available.

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