You have to sort a list L, consisting of a sorted list followed by a few…

Correct answer: Insertion sort

Why insertion sort is most suitable:

• Insertion sort is adaptive: it builds a sorted prefix and inserts each new element into its correct position by shifting elements.

• Performance depends on the number of inversions (misplaced pairs). For a nearly-sorted list the number of inversions is small, so runtime is close to linear.

• Best-case time complexity is O(n) when the list is already sorted; average/worst-case is O(n^2) but that is not reached for mostly-sorted inputs.

• Insertion sort is in-place and stable and has low overhead, making it efficient for small numbers of random elements appended to an already-sorted list.

Short comparison with other methods:

• Bubble sort: An optimized bubble sort can detect a fully sorted list, but it tends to perform many swaps and passes and is usually slower than insertion sort on nearly-sorted data.

• Selection sort: Not adaptive; always performs O(n^2) comparisons regardless of initial order, so it does not exploit the existing sorted portion.

• Quick sort: Good for random data on average, but it is not adaptive to existing order and has higher overhead for small perturbations; it can also degrade on already-sorted inputs without careful pivot selection.

Summary: For a list that is largely sorted with a few random elements, insertion sort minimizes work by only moving the misplaced elements and is therefore the most suitable choice.