Consider the same setup as in the previous question. In what order are the keys popped off of the stack when the mystery function is called with a pointer to the root of the binary search tree? $1.5,1,3,2,4,6,72.1,2,3,4,5,6,73.3,4,2,1,5,6,74.2,4,3,1,7,6,5$