Compare two diverging lenses that are similar except that lens B is rated at 20 Diopters, whereas lens A is rated at 10 Diopters. The focal length of lens B is ________.
1) Twice the focal length of lens A
2) 1/4 of the focal length of lens A
3) 1/2 of the focal length of lens A
4) 1/sqroot2 of the focal length of lens A