Consider the following transshipment problem.$$ The shipping cost per unit between nodes $1$ and $2$ is $$10,$ while the shipping cost per unit between nodes $2$ and $3$ is $$12.$ What is the objective function?

$$

A$.$

Max $10$X$12+12$X$23$

B$.$

Min X$12+$ X$23$

C$.$

Min $10$X$12+12$X$23$

D$.$

Max X$12+$ X$23$

E$.$

Min $-10$X$12-12$X$13$