Final answer:
Plants use air (carbon dioxide) and water to obtain carbon, hydrogen, and oxygen atoms needed for photosynthesis, which produces glucose and oxygen using sunlight. So the correct option is A.
Step-by-step explanation:
The source of carbon, hydrogen, and oxygen atoms for a plant to produce energy is A. Air and water. Through photosynthesis, plants use sunlight to convert carbon dioxide (taken from the air) and water (absorbed through the roots) into glucose, a carbohydrate, and oxygen. Glucose acts as the plant's food source, while oxygen is released as a byproduct. The photosynthesis equation can be summarized as: in the presence of sunlight, carbon dioxide + water → glucose + oxygen. If plants do not have sufficient sunlight as an energy source or enough water, they will not be able to perform photosynthesis, which would negatively impact their survival and that of organisms depending on them.