What statement is true concerning the effect of elevating the temperature of the oily- water mixture associated with an oily-water separator?

Correct Answer: Option C — Heating the oily-water mixture decreases the viscosity of the oil and increases the specific gravity differential between the oil and water.

Heating the mixture reduces the oil's viscosity, allowing droplets to coalesce and rise more rapidly. Simultaneously, it increases the density differential between the oil and water, as water expands less than oil when heated. This enhances the efficiency of the gravity-based separation process within the oily-water separator unit.