A lens of glass, refractive index 1.5 has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75,it will behave as a
| A. |
convergent lens of focal length 3.5 R |
 |
| B. |
convergent lens of focal length 3.0 R |
| C. |
divergent lens of focal length 3.5 R |
| D. |
divergent lens of local length 3.0 R |