Direct contact enables conduction of heat

Steps:

• Identify the setup: hotplate touches metal pan directly.
• Recall heat transfer modes: conduction (solids, contact), convection (fluids, motion), radiation (waves, no medium).
• Match scenario: no fluid movement or waves involved, just solid-to-solid contact.
• Conclude: energy passes via vibrating particles in direct touch.

Why A is correct:

• Conduction transfers thermal energy through direct molecular contact in solids, as defined by Fourier's law (q = -k ∇T), where heat flows from hotplate to pan via atomic vibrations.

Why the others are wrong:

• B: Convection requires fluid currents to carry heat, absent here.
• C: Diffraction is wave bending around obstacles, unrelated to thermal energy.
• D: Refraction is light bending in media, not a heat transfer process.

Final answer: A