Here's a problem to solve: Heat transfer is part of everyday life. Which of these examples involving heat transfer occurs mainly by conduction?

Among the 4 following options, which is the correct answer?

- A: The sun warms the ground.
 
- B: A hot oven warms a cold kitchen.
 
- C: A campfire warms a person's hands.
 
- D: Hot soup warms a metal spoon handle.
 