Cho hàm số y = f(x) có đạo hàm tại x0 là f'(x0). Khẳng định nào sau đây sai?

A. $f\text{'}\left(x_0\right)=\underset{x\to x_0}{\lim }\frac{f\left(x\right)-f\left(x_0\right)}{x-x_0}$

B. $f\text{'}\left(x_0\right)=\underset{∆x\to 0}{\lim }\frac{f\left(x_0+∆x\right)-f\left(x_0\right)}{∆x}$

C. $f\text{'}\left(x_0\right)=\underset{h\to 0}{\lim }\frac{f\left(x_0+h\right)-f\left(x_0\right)}{h}$

D. $f\text{'}\left(x_0\right)=\underset{x\to x_0}{\lim }\frac{f\left(x+x_0\right)-f\left(x_0\right)}{x-x_0}$