- If something releases something else then that something is the source of that something else
- Plants are a source of oxygen through photosynthesis
- So, plants release oxygen during photosynthesis

- A plant absorbs carbon dioxide from the air to perform photosynthesis
- To absorb something can mean to take something in
- Hence, a plant takes in carbon dioxide to perform photosynthesis

- Plants release oxygen during photosynthesis
- A plant takes in carbon dioxide to perform photosynthesis
- So, plants take in carbon dioxide and release oxygen during photosynthesis

Therefore, plants take in carbon dioxide and release oxygen during photosynthesis
Which is a process that occurs during photosynthesis?
- A plant absorbs carbon dioxide from the air to perform photosynthesis 
- If something releases something else then that something is the source of that something else 
- Plants are a source of oxygen through photosynthesis 
- To absorb something can mean to take something in