The door of a microwave oven contains a metal mesh with holes roughly 1mm in diameter. Observers can see the food cooking, yet the microwaves do not escape. Which statement best accounts for this?
(a) The holes are larger than both wavelengths, but visible light is more energetic and therefore passes through.
(b) The holes are much smaller than the microwave wavelength but far larger than the wavelength of visible light.
(c) Microwaves are strongly absorbed by the glass behind the mesh, whereas visible light is not.
(d) The metal conducts electricity so effectively that it reflects lower-frequency microwaves, while the higher-frequency visible light slips through the openings.