A plano-convex lens having radius of curvature of first surface 2 cm exhibits focal length of f1 in air

A plano convex lens having radius of curvature of first surface 2 cm exhibits focal length of f1 in air. Another plano-convex lens with first surface radius of curvature 3 cm has focal length of f2 when it is immersed in a liquid of refractive index 1.2. If both the lenses are made of same glass of refractive index 1.5, the ratio of f1 and f2 will be :- 

(1) 3 : 5 

(2) 1 : 3

(3) 1 : 2 

(4) 2 : 3                               (JEE-2025)