Which statement best summarizes Niels Bohr's complementarity principle? Light incident on a metal surface results in the emission of a photon. Light incident on a metal surface results in absorption of energy. The wave theory and the particle theory of light coexist. The theory of wave-particle duality does not hold true.

The complementarity principle says that when one wishes to study the behavior of light on an atomic scale, the wave and particle natures of light must both be observed simultaneously to present a more complete overall description.

(On the other hand, when observing light on a macroscopic scale, one does not typically need to consider both wave and particle natures simultaneously.)