You are given two Finite Automata $($FA$),$ FA$1$ and FA$2,$ as shown below.

On a piece of paper, use the algorithm of Kleene's theorem to construct FA$3,$ the union

language FA$1+$ FA$2.$ Then answer the following question:

What language does FA$3$ define?

a finite language

a language of any string that ends in $"b".$

a language of any string that ends in $"$a$"$ or has $"a{b}^{?}$ in it$.$

a language of any string that ends in $"$a$".$