Diffraction at a Single Slit question from MHT CET 2021 (22 Sep, Shift 1)

Answer: (a)

1. Linear width of central maximum $W = \dfrac{2D\lambda}{a}$, where $D$ is the slit-to-screen distance.
2. It depends on $\lambda$ (and hence on frequency, since $\lambda = c/\nu$) and on slit width $a$.
3. The source-to-slit distance does not appear (parallel beam).
4. So the working gives (c) distance between slit and source.