Final answer:
The correct statement is option (c), which reflects the Extreme Value Theorem stating that a continuous function on a closed interval must attain a maximum and a minimum. Other options are not necessarily true without additional information about the function or its derivatives.
Step-by-step explanation:
If f is a continuous function on the closed interval [a,b], one statement that must be true is option (c): There is a number c in the closed interval [a,b] such that f(c) ≥ f(x) for all x in [a,b]. This statement is a direct consequence of the Extreme Value Theorem, which ensures that a continuous function on a closed interval must attain a maximum and a minimum value on that interval. Therefore, there exists at least one point c where f(c) is maximum (or equivalently, greater than or equal to any other value the function takes on the interval).
In contrast, statement (a) would require the existence of a root, which cannot be guaranteed without additional information about the values of f(a) and f(b). Statement (b) assumes a strict inequality without knowledge of how f(a) and f(b) relate to the other values of f(x). Statement (d) refers to the Mean Value Theorem but requires f to be differentiable, which is not given in the question. As for statement (e), it is an expression of the Mean Value Theorem, which states that for a continuous function that is also differentiable on the open interval (a,b), there exists some c in (a,b) such that f'(c) = (f(b)-f(a))/(b-a). However, differentiability is not guaranteed in this question, so this statement is not necessarily true either.