A converging lens forms a real image I of an object on its principal axis. A rectangular slab of refractive index μ and thickness x is introduced between I and the lens, I will move
(a) towards the lens (μ-1)x
(b) towards the lens by (1- 1/μ)x
(c) away from the lens by (μ-1)x
(d) away from the lens by (1- 1/μ)x