Multiple choice

Air supplies _______ and ______to crops, living beings

  1. C and H

  2. C and O

  3. H and O

  4. C, H and O

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Air provides carbon (C) from carbon dioxide and oxygen (O) from atmospheric oxygen. Hydrogen (H) comes from water. Plants use all three elements (C, H, and O) to build carbohydrates through photosynthesis. The other combinations are incomplete.