What three essential nutrients are absorbed from the air by plants?

Plants absorb three essential nutrients from the air: carbon, hydrogen, and oxygen. Carbon is primarily taken in through the process of photosynthesis, where plants utilize carbon dioxide from the atmosphere to synthesize organic compounds necessary for growth. Hydrogen is absorbed as part of water, which is essential for various biochemical processes within the plant, including photosynthesis and nutrient transport. Oxygen, which is produced during photosynthesis, is also a critical element that plants utilize for respiration and metabolic activities.

The other options contain nutrients that are either not absorbed directly from the air or are less relevant to the essential nutrient classification. For instance, nitrogen is indeed a vital nutrient for plants, but it is mainly absorbed from the soil in forms like nitrate or ammonium, not directly from the air. The other elements listed, such as manganese, potassium, iron, zinc, and copper, are micronutrients that plants require for various functions but are also sourced from the soil rather than the air. Therefore, the trio of carbon, hydrogen, and oxygen stands out as the essential nutrients absorbed directly from the air.