Which of the following is a stable sorting algorithm?Merge sort Typical in-place quick sortHeap sortSelection sort

Merge sort is a stable sorting algorithm.

Here's why:

1. Stable sorting algorithms maintain the relative order of records with equal keys (i.e., values). In other words, a sorting algorithm is stable if whenever there are two records R and S with the same key and with R appearing before S in the original list, R will always appear before S in the sorted list.

2. When merge sort is implemented properly, it ensures that the order of equal elements is maintained, thus making it a stable sort.

3. On the other hand, typical in-place quick sort, heap sort, and selection sort are not stable. They may change the relative order of records with equal keys. For example, in quick sort, the pivot element is moved to its final position in the sorted array with all smaller elements moved before it and all greater elements moved after it, which can change the relative order of equal keys.