Final answer:
Radiation becomes the dominant mode of heat transfer as a fire grows in size, due to its ability to emit energy via infrared waves, which can travel without a medium and are felt as heat on the skin from a distance. The correct answer is option B. Radiation
Step-by-step explanation:
The question concerns the dominant mode of heat transfer as a fire grows in size. Among the different methods of heat transfer, which are conduction, convection, and radiation, radiation becomes the dominant mode when a fire grows. This is because as the fire increases in size, more energy is emitted in the form of infrared radiation, which can transfer heat over larger distances without requiring a medium, in contrast to conduction and convection.
While conduction is the heat transfer through direct contact and is typically much slower, convection is the transfer of heat by the movement of fluids (such as air) but is less efficient over longer distances compared to radiation.
When close to a fire, individuals can often feel the warmth without direct contact, indicating that infrared radiation is at work. In the context of a fire, radiation can be felt as heat on the skin even without looking at the fire itself, which is testament to its effectiveness in transferring thermal energy over a distance. With fire's visibility due to visible light being dramatically less effective in transferring heat compared to infrared radiation, it is clear that radiation is significant for heat transfer as fires increase in size.