Units & Dimensions question from JEE Main 2021 (27 Aug, Shift 1)

Answer: (c)

1. Relative permeability $\mu_r = \mu/\mu_0$ is a ratio of like quantities, so it is dimensionless.
2. Power factor $\cos\phi$ and quality factor $Q = \omega L/R$ are also pure numbers.
3. $\mu_0$ comes from $B = \dfrac{\mu_0 I}{2\pi r}$, so $[\mu_0] = [\mathrm{MLT^{-2}A^{-2}}]$, not dimensionless.
4. So the answer is (c) $\mu_0$.