Now consider again the lenses to be in contact with each other but made of material of refractive index 1.2. The system is immersed in a medium of refractive index μ and it is found that the focal length of the system remains numerically the same as when in air. Therefore, μ is
(a) < 1.2
(b) 1.2 < μ < 1.5
(c) > 1.5
(d) = 1.5
