If f(x) is differentiable at a point x - c, then f(a ) must also be continuous at a = c. In particular, any differentiable function must be continuous at every point in its domain. The converse does not hold: a continuous function need not be differentiable. Which of the following is a continuous function that is not differentiable on its domain? Select one: O a. f(a) = |z| O b. f(x) = V2x + 1 O c. f(x) = 0 O d. f(ac) = 2