Prove that the radius of convergence of complex f' (z) is the same as the radius of convergence of f(z).
a) The radius of convergence is always smaller for f′ (z).
b) The radius of convergence is always larger for f′(z).
c) The radius of convergence is the same for f(z) and f' (z).
d) The radius of convergence cannot be determined from the given information
