1. (18 points) Suppose the following tree is obtained at a certain point during Branchand-Bound procedure. The numbering of the subproblems indicate the order of the nodes that are considered. For each subproblem, ' Z ' value indicates its objective function value and you can assume that the decision variables are integer if Z is a) Is the objective of the problem maximization or minimization? Clearly explain why. b) Indicate which subproblems are fathomed in the order of their pruning decision. For each fathomed node, clearly explain the reason. c) Can the Branch-and-Bound procedure be stopped at this point? Explain your answer. If you think the procedure can be stopped, give the optimal solution value. If you think the procedure is not completed, provide the tightest lower bound and the tightest upper bound values