Let f be a continuous and strictly increasing function on the closed interval [a,b] with range [c,d]. Which of the following statements is true?
a) f−1 is differentiable on (c,d).
b) f−1 is strictly decreasing on [c,d].
c) f−1 is continuous on [c,d].
d) f−1 may be discontinuous at c or d even though f is continuous.