Given an array of n numbers, a median x exists such that x is larger than at least n/20 of the numbers and smaller than at lest n/20 numbers. If this x is used as a pivot in quick sort. What is the worst case running time of this algorithm?
a. O(n)
b. O(n11/10)
3. O(nlogn)
4.O(n2)
5. O(n10/11 log n)