Question

when we exhale carbon dioxide, what do plants provide in return? oxygen nitrogen carbon dioxide water vapor

Explanation:

Plants perform photosynthesis, using carbon dioxide (exhaled by us) and water to produce glucose and oxygen. So in return for the carbon dioxide we exhale, plants provide oxygen. Nitrogen is not a direct product of this exchange related to our exhaled CO₂, plants don't provide CO₂ back in this context (they take it in), and water vapor is not the main return related to CO₂ exchange.

Answer:

A. oxygen