Which of the following statements is true?

Dissolved oxygen in wastewater is an important indicator of the water's organic and biological processes. In fresh, uncontaminated water, there is typically higher dissolved oxygen due to the presence of aquatic plants and other factors that contribute to oxygenation. Conversely, wastewater, especially when it is stagnant or polluted, tends to have lower levels of dissolved oxygen due to the decomposition of organic matter and the consumption of oxygen by bacteria and other microorganisms. Therefore, a higher level of dissolved oxygen in wastewater can indicate that the water is less contaminated and has fresher qualities.

In contrast, high turbidity is generally a sign of suspended particles in water, which often implies that the water could be dirty or contaminated. Nutrients typically accumulate in wastewater but can decrease with effective treatment processes. Lastly, bacteria thrive in environments with organic matter but are not inherently suited to sterile environments where their food sources are absent.