Resolving Power question from MHT CET 2026 (20 Apr, Shift 2)

Answer: (c)

1. Resolving power of a microscope $= \dfrac{2n\sin\theta}{1.22\lambda}$.
2. It increases with refractive index $n$ of the medium (oil immersion) and decreases with larger $\lambda$; the eyepiece has no effect.
3. So the answer is (c) increase the refractive index of the medium between the object and objective lens.