Which graph best represents the relationship between dissolved oxygen levels and water temperature?

The relationship between dissolved oxygen levels and water temperature is typically characterized by a negative correlation. As water temperature increases, the dissolved oxygen levels tend to decrease. This happens because warmer water holds less oxygen than colder water, making it more challenging for aquatic organisms that depend on oxygen to survive.

In natural aquatic ecosystems, this negative correlation can be observed in various situations, such as during summer months when water temperatures rise, leading to reduced oxygen availability. This relationship is crucial for understanding aquatic life and the health of ecosystems, particularly as temperatures fluctuate due to seasonal changes or climate change.

The other options do not accurately reflect this established relationship. A positive linear correlation implies that as one variable increases, the other also increases, which is not the case here. A bell-shaped curve suggests that there is an optimal temperature range for oxygen levels, which does not represent the general trend. A constant line would indicate no relationship at all, which fails to account for the significant impact temperature has on dissolved oxygen levels.