Name two divide and conquer sorting algorithms.

Quicksort and mergesort.

Name three well-known quadratic time sorting algorithms.

Bubblesort, selection sort, and insertion sort.

In the comparison model of computation, the number of comparisons
any sorting algorithm must make to sort n items is, in the worst case,
at least what?

The base to logarithm of n!, which is Theta(n log n).