Final answer:
Certain areas near a lightbulb are warmer due to the radiation of heat, as heat transfers to Xavier's hand via infrared radiation emitted by the lightbulb without needing physical contact or fluid movement.
Step-by-step explanation:
The reason why certain areas around the lightbulb are warmer than others when Xavier places his hand near it is due to C) Radiation of heat. This is because heat can transfer even through empty space, without the need for a medium, in the form of electromagnetic waves such as infrared radiation that the lightbulb emits. Unlike conduction, which requires physical contact, or convection, which involves the macroscopic movement of fluids, radiation can occur across a vacuum or air, allowing the heat to reach Xavier's hand without requiring direct contact with the lightbulb or heated air circulation.