Explain why the function is discontinuous at the given number a. (Select all that apply.) a. f(x) = x2 − 3x x2 − 9 if x ≠ 3 1 if x = 3 a = 3 f(3) is defined and lim x→3 b. f(x) is finite, but they are not equal. c. f(3) is undefined. d. lim x→3 f(x) does not exist. e. lim x→3+ f(x) and lim x→3− f(x) are finite, but are not equal. f. none of the above