Heaps

Consider the following statements: I. The smallest element in a max-heap is always at a leaf node II. The second largest element in a max-heap is always a child of the root node III. A max-heap can be constructed from a binary search tree in $\Theta(n)$ time IV. A binary search tree can be constructed from a max-heap in $\Theta(n)$ time Which of the above statements are TRUE?