Consider the following maximal flow problem.

What is the objective function?

Question $4$ options:

Max X$24+$ X$34$

Min X$12+$ X$13$

Max $4*$X$12+5*$X$13+2*$X$23+3*$X$24+6*$X$34$

Max X$12+$ X$13+$ X$23+$ X$24+$ X$34$