Final answer:
The characteristics of the interference pattern in a double-slit experiment are mainly determined by the wavelength of the light, which dictates the spacing and overall layout of the bright and dark fringes, although the distance between the slits is also crucial to the pattern.
Step-by-step explanation:
When dealing with monochromatic light and a double-slit interference experiment, the characteristics of the interference pattern are predominantly determined by three key factors: the wavelength of the light (λ), the distance between the slits (d), and the width of the slits. Option C: The wavelength of the light is the correct answer because the pattern's fringe spacing and overall appearance are directly related to it, as seen in the formulas relating the angle of interference (θ) and the order of interference (m). However, Option D: The distance between the slits is also a crucial factor impacting the interference pattern. Evenly spaced bright spots imply that the interference arises from two slits (double-slit characteristic), while the diminishing intensity of the bright spots away from the center is due to single-slit diffraction effects. If the bright spots fade on either side of the center, it suggests that the single-slit diffraction is affecting the double-slit interference pattern, often because the slit width is on the same order of magnitude as the light's wavelength. To determine whether the slit width or the separation between slits is smaller, we need additional information regarding the exact measurements or the relationship between the intensity of the bright fringes and their fading which is not provided in the question. However, generally, the separation between the slits is larger compared to the slit width in a typical double-slit setup to ensure clear interference patterns.