Answer 1

Base case is the case for which we know the answer for.

The base case in a recursive algorithm is the case that is no longer recursive. For example, here’s a recursive algorithm to compute n! (n factorial):

If n = 1, the answer is 1
Otherwise, the answer is n(n−1)!

In this case we know we need to return 1 if the n=1 hence it is the base case.