Answer:
Input: oxygen (or air generally), breathed in by the scuba diver
Output: carbon dioxide exhaled by the scuba diver
Explanation:
The scuba gear is absolutely essential to sustaining this activity by sea divers. It serves the purpose of recycling the air breathed out by the person by filtering out the carbon dioxide. It also makes up for the oxygen that gets used so that the diver can continue breathing in a circuit. Thus, oxygen is considered as input and CO2 as output in this case.
