Let f: [0, 2] → R be a twice differentiable function such that f''(x) > 0 for all x ∈ [0, 2]. What is the set of possible options for the values of x?

a. [0, 2]
b. (0, 2)
c. (0, 2) ∪ {0, 2}
d. (0, 2]