The quantity of dissolved oxygen in water is a function of:

• A. pH, turbidity, and conductivity
• B. Temperature, pressure, and salinity
• C. Light, area, and organisms
• D. Organic matter, sediment and energy

Answer: (B)

The quantity of dissolved oxygen in water is primarily influenced by temperature, pressure, and salinity.

As temperature increases, the solubility of oxygen in water decreases, meaning warmer water typically holds less dissolved oxygen than cooler water. Pressure also impacts dissolved oxygen; at greater depths, the increased pressure allows water to hold more gases, including oxygen. Salinity affects dissolved oxygen as well; higher salinity levels can decrease oxygen solubility because it alters the water's chemical properties.

The other factors presented in the options don't have a significant direct relationship with dissolved oxygen levels. For instance, while pH can influence aquatic life and its ability to thrive in the water, it does not directly determine the amount of oxygen dissolved. Similarly, turbidity and conductivity relate more to water clarity and ion presence, and while light, area, and organisms are certainly important in the broader ecosystem dynamics affecting oxygen levels (e.g., photosynthesis and respiration), they aren't primary controlling factors of dissolved oxygen concentration itself.