Answer: C
If root node is 190, in order to find 88 we need to traverse the left sub-tree because in the right sub-tree every element will be greater than 190.
Now 88 is greater than 60, so we go to right where we find 90 which is greater than 88, so now we traverse left sub-tree of 90. We find 85 which is less than 88, so we go right and find our key 88.