How does temperature affect dissolved oxygen (DO) levels?

Dissolved oxygen (DO) levels are significantly affected by temperature, with the relationship being an inverse one. As the temperature of water increases, the capacity of that water to hold dissolved oxygen decreases. This is a fundamental principle in aquatic chemistry, where warmer water can hold less oxygen than cooler water.

In cooler temperatures, water can maintain higher levels of dissolved oxygen, which is crucial for the survival of aquatic organisms, such as fish and invertebrates. Therefore, lower temperatures lead to higher levels of dissolved oxygen, making this answer the most accurate reflection of how temperature impacts DO levels in aquatic environments.

The other choices present variations that don't accurately reflect the scientific understanding of this relationship. For instance, while it might seem intuitive to think that warmer water could enhance biological activity and thus increase DO, the physical properties of water dictate otherwise.