How many number of comparisons are required in insertion sort to sort a file if the file is sorted in reverse order?Select one:N^2 N-1NN/2

The number of comparisons required in insertion sort to sort a file if the file is sorted in reverse order is N^2.

Here's why:

Insertion sort works by comparing each element in the list with the previous elements. If the list is sorted in reverse order, each element will need to be compared with all the previous elements.

For example, the first element will be compared with 0 other elements, the second element will be compared with 1 other element, the third element will be compared with 2 other elements, and so on.

So, the total number of comparisons will be 0 + 1 + 2 + 3 + ... + (N-1), which is the sum of the first N-1 natural numbers.

The formula for the sum of the first N natural numbers is N*(N+1)/2. But since we're starting from 0, we subtract 1 from N, giving us (N-1)*N/2.

However, because each comparison involves two elements, we multiply the result by 2, giving us N^2 comparisons.