Final answer:
The correct term for the deep ocean waters' overturning circulation is d. thermohaline flow, which is a global ocean circulation process driven by temperature and salinity differences.
Step-by-step explanation:
Deep ocean waters flow in an overturning circulation called d. thermohaline flow. This process is driven by differences in water temperature and salinity, which affects density and causes water to move in a large-scale pattern across the world's oceans.
Ocean upwelling is a related but distinct phenomenon where deep ocean waters rise to the surface, driven by offshore winds blowing along coastlines, which facilitates the cycling of nutrients and supports marine productivity.