Question $18$ to Question $20$ is based on this problem.

A railroad needs to move the maximum amount of material through its rail network. The numbers on arcs represent maximum flow. Formulate the LP model to determine this maximum amount based on the following network diagram.

Table $8-$ Exam $2.$png

Let Xij be the amount of material flowing from node i to node j$.$

What is the objective function in the maximal flow problem depicted in the above diagram?

Group of answer choices

Max X$13$Let $j$ be the amount of material flowing from node $i$ to node $j.$

What is the objective function in the maximal flow problem depicted in the above diagram?

Max X$12+$ X$25+$ X$56$

Max X$13+$ X$35+$ X$34+$ X$46$

Max X$12$

Max X$61$