Final answer:
When a fluid flows over a solid with a different surface temperature, the type of heat transfer that occurs is convection, which involves the movement of the fluid.
Step-by-step explanation:
The type of heat transfer that occurs when a fluid flows over a solid whose surface temperature is different from that of the fluid is convection. Convection is characterized by the macroscopic movement of a fluid, which can either be a liquid or a gas. This movement transfers heat from the warmer parts of the fluid to the cooler parts, or from the heated solid to the fluid, and vice versa.
Conduction is another type of heat transfer where heat is transferred through direct contact without any movement of the matter itself. It is not the primary mechanism at work when a fluid is moving over a solid. Radiation, on the other hand, is heat transfer that involves electromagnetic waves and does not require a medium. Therefore, for the scenario described, the correct answer is convection.