Consider a binary min-heap, such as would be used to order the elements ina priority queue in which the lowest number item had the highest priority. Which of the following properties are always true of a binary min-heap? Select all that apply. 1) The element in the heap with the smallest value is at the root. 2) The value of the left child of an element in the heap is always greater than the value of the right child of that element. 3) A binary heap is a full binary tree: that is, every level of the binary tree is completely filled with elements; equivalently, every node other than the leaves has two children. (So that the total number of elements in the heap is always 2n-1 for some n). 4) If you do a preorder traversal of a binary min-heap, you are guaranteed to print out its elements in sorted order. 5) A binary heap is a complete binary tree: that is, every level of the binary tree except possibly the lowest level is completely filled, and if the lowest level is not filled in, it is filled left-to-right. 6) The value of an element in the heap is alwaus greater than the value of its parent element in the heap