The condition under which a microwave oven heats up a food item containing water molecules most efficiently is:

Options

A. The frequency of the microwaves has no relation with natural frequency of water molecules.
B. Microwaves are heat waves, so always produce heating
C. Infra-red waves produce heating in a microwave oven
D. The frequency of the microwaves must match the resonant frequency of the water molecules

Answer

D