A point object is placed at 30 cm from a convex glass lens `(mu_(g) = (3)/(2))` of focal length 20 cm. The final image of object will be formed at infinity if
A. another concave lens of focal length 60 cm is placed in contact with the previous lens
B. another convex lens of focal length 60 cm is placed at a distance of 30 cm from the first lens
C. the whole system is immersed in a liquid of refractive index 4/3
D. the whole system is immersed in a liquid of refractive index 9/8
