For the Job assignment problem, given the data below, find the unique job assignment for $A,B,C,D$ that results in the most minimum cost. Derive this by applying branch and bound technique on a state space tree. Draw this tree, illustrating work. Finally list out the unique job assignment for $A,B,C,D$ and the cost.

Note: The graph $($tree$)$ that we worked on in class, is called the state space tree.