AIIMS 2019 Physics Young's Double Slit Experiment Assertion Reason Question

The assertion is true because the distance between the positions of bright and dark fringes remains constant in Young's Double Slit Experiment (YDSE) for a given setup, as the fringe width (β) is uniform across the screen. The reason is also true, as fringe width is defined by the formula β = λD/d, where λ is the wavelength, D is the distance from the slits to the screen, and d is the slit separation; however, it does not explain why the distance between bright and dark fringes remains the same, since this distance is a consequence of the uniformity of β rather than a direct result of the formula itself. Option A is incorrect because, while both statements are true, the reason does not correctly explain the assertion. Options C and D are incorrect as they misrepresent the truth of both the assertion and the reason.