能帮我看看吗？证明或找个反例。谢谢

f(z) is differentiable on region D. Inside D there is a line segment C with end points a and b. Proof that there is a number k, |k|<=1 and a point p on C such that f(b)-f(a)=k(b-a)f'(p), all the function and numbers are complex。

人工智能说证不了：Without additional assumptions on the function f(z), such as being entire or satisfying certain conditions, it is not possible to prove the above statement in general.