Hàm số nào sau đây gián đoạn tại điểm x0 = 1; f(x) = (x^2 - 1)

A. $f\left(x\right)=\left\{\begin{array}{l}\frac{x^2-1}{x-1},khix\ne 1\\ 2\text{ ,}khix=1\end{array}\right.$

B. $g\left(x\right)=\left\{\begin{array}{l}\frac{x^4-1}{x-1},khix\ne 1\\ \text{4 ,}khix=1\end{array}\right.$

C. $h\left(x\right)=\left\{\begin{array}{l}\frac{\sqrt{x}-1}{x-1},khix\ne 1\\ \frac{1}{2}\text{ ,}khix=1\end{array}\right.$

D. $k\left(x\right)=\left\{\begin{array}{l}\frac{x^3-1}{x-1},khix\ne 1\\ \text{3 ,}khix=1\end{array}\right.$