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Which of the following functions are continuous but not differentiable at $x=1$?

I. $y=\sqrt[3]{x-1}$II. $y=|1-x|$III. $y=(1-x) \cdot |1-x|$IV. $y = \cfrac{1}{x-1}$

I only.

I and II only.

I, II, and III only.

I, II, III, and IV.