Which of the following statements is/are true?

if f '(x) > 0 on (a, b), then f(x) is increasing on [a, b].
if f(a) = f(b), then there exists a number c in (a, b) such that f '(x) = 0.
if f(x) is differentiable at x = c, then f(x) is continuous at x = c.
i only
ii only
i and iii only
i and ii only