Electrons show diffraction effects because their de Broglie wavelength is similar to?

Electrons show diffraction effects because their de Broglie wavelength is similar to the spacing between atomic layers in a crystal or the size of a narrow aperture, which acts as a diffracting object. This similarity is crucial for the electron wave to interact with the atomic lattice or obstacle in a way that produces a measurable diffraction and interference pattern, which confirms their wave-like behavior.