Question

The interference pattern seen when light passes through narrow, closely spaced slits, is due to

Answer 1

Answer: Diffraction

Diffraction  is a characteristic phenomenon that occurs in all types of waves .

In this sense,  diffraction happens when a wave (the light in this case) meets an obstacle or a slit .When this occurs, the light bends around the corners of the obstacle or passes through the opening of the slit that acts as an obstacle, forming multiple patterns with the shape of the aperture of the slit.

Note that the principal condition for the occurrence of this phenomena is that the obstacle must be comparable in size (similar size) to the size of the wavelength.