b
Refractive index of a medium wrt violet light is more than wrt red light. So deviation in case of violet ray is more than that of red red ray.

Hence for converging lens ie convex lens a beam of violet parallel rays converges nearer to the lens than the beam of red parallel rays. So \(f_V < f _R\)

For diverging lens ie concave lens a beam of violet parallel rays appears to diverge from more closer point from the lens than the beam of red parallel rays. So \(F _{V }> F _R\), as the focal length of concave lens is negative.