Which part must have the right amount of oil to help prevent overheating in hot weather?

Answer: D — Engine

Engine oil is essential for both lubrication and heat management inside the engine. It forms a protective film between moving metal parts, reducing friction and wear. As it circulates, it also carries heat away from hot components like pistons and cylinder walls to the oil pan where it can dissipate. In hot weather, engines run hotter and oil can thin or degrade; if the oil level is too low, there isn’t enough oil to form an adequate film or to carry away heat. That raises friction and creates hotspots, increasing the risk of overheating and engine damage. So keeping the right amount of oil is crucial for preventing overheating. Radiator coolant handles cooling separately, transmission fluid cools and lubricates the transmission, and the alternator isn’t cooled by engine oil.