Final answer:
Fish are found in deeper waters of a lake during warmer parts of the day because temperature affects the solubility of gases in water.
Step-by-step explanation:
The statement that best explains why fish are found in deeper waters of a lake during warmer parts of the day is the one that refers to the solubility of gases in water. Temperature affects the solubility of gases, with solubility typically decreasing as temperature increases. As the day gets warmer, the water temperature rises, causing the solubility of gases in the water to decrease. This makes the deeper waters a more favorable habitat for fish because there is a higher concentration of dissolved oxygen, which they need to survive.