Question: Which of the following statements is true regarding heat transfer?

Options:

1. Heat flows from cold to hot spontaneously
2. Heat transfer requires a medium
3. Heat can be transferred by conduction, convection, and radiation
4. Heat transfer is always efficient

Correct Answer: Heat can be transferred by conduction, convection, and radiation

Solution:

Heat can be transferred by conduction, convection, and radiation, which are the three primary modes of heat transfer.