Answer will be Merge Sort
In merge sort we divide the array in 2 subarrays, then again divide it in 2 subarrays, like that it divide entire array
And time of merging, we merge 2 subarrays, again merge next two sub arrays
So, here input hardly matters to sort the array
But if we consider quick sort , here initial ordering matters. Because if the array is increasing or decreasing order , quick sort takes maximum running time to find, is the array is sorted or not
Similarly, for insertion sort and selection sort, for sorted and unsorted input running time differs in every case