Dull surfaces absorb and emit radiation well but reflect poorly

Steps:

• Recall that surface properties for thermal radiation depend on texture: shiny surfaces reflect well, dull (matt) surfaces do not.
• Dull surfaces absorb most incident radiation instead of reflecting it, making them good absorbers.
• By Kirchhoff's law, good absorbers are also good emitters at thermal equilibrium.
• Thus, dull surfaces are poor reflectors, confirming the combination of good emitter, good absorber, and poor reflector.

Why B is correct:

• Matches Kirchhoff's law of thermal radiation, where emissivity equals absorptivity, and low reflectivity follows for opaque dull surfaces.

Why the others are wrong:

• A: Contradicts law; good emitters must be good absorbers.
• C: Dull surfaces are poor reflectors, not good ones (that's shiny surfaces).
• D: Dull surfaces are good emitters and absorbers, not poor.

Final answer: B