Suppose that f(x) is a twice-differentiable function on the closed interval [a, b]. if there is a number c, a < c < b, for which f' (c) = 0, which of the following must be true?

i. f(a) = f(b)

2. f has a relative extremum at x=c.

3. f has a point of inflection at x= c.

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