Let f(x) = |x + 1|. Which of the following statements about f is true? Select one: O a. f is differentiable but not continuous at x = - 1. O b. f is continuous and differentiable at x = 1. O c. f is differentiable and continuous at x = - 1. O d. f is continuous but not differentiable at x = 1. O e. f is differentiable but not continuous at x = 1