List a few reason why the oxygen level decreases in the cave.

Lack of circulation, lack of plants

Explanation:

Oxygen levels decrease in caves because if a person is inside they are using up the oxygen and repalcing it with carbon dioxide with only a small entrance for new oxygen to come inside.  Additionally, the lack of sunlight inside a cave means that plants can not go through photosynthesis and survive, so no plants can create the oxygen inside the cave.

answer; inductive techniques;