Let f be a function defined as f(x) = 2x log2x over the interval [1, 2]. What conclusion can be made about the value of k such that f(k) = 4?
1) The value of k must be 18.
2) The value of k must be between 1 and 2.
3) No conclusion can be made about k because 1 < 2 < 4.
4) No conclusion can be made about k because f(x) is not continuous over the interval.