Final answer:
The global conveyor belt circulates warm and cold ocean currents across the planet and is driven by differences in water density resulting from temperature and salinity variations, not solely by surface winds.
Step-by-step explanation:
The correct statement about the global conveyor belt is b. It circulates warm and cold ocean currents. The global conveyor belt, also known as thermohaline circulation, is a vast network of interconnected ocean currents that move water around the globe. It is driven by differences in water density, which are affected by temperature (thermal) and salinity (haline), hence the term 'thermohaline'. This system plays a crucial role in transferring heat from the equator to the poles and in influencing climate and weather patterns across the planet. The notion that it is a man-made structure or that it only operates in the Atlantic Ocean is incorrect. Additionally, while surface winds influence ocean currents, they are not the sole driver of the global conveyor belt.