Which of the following statements is true?

Question $6$ options:

A$)$

Since there is a cost to ship product from each warehouse to each barn we need a cost coefficient for each decision variable $($cell$).$

B$)$

The objective function $($cell$)$ of a logistics problem specifies maximization.

C$)$

To define a linear optimization model we consider first the constraints.

D$)$

To solve logistics problems we use exclusively non$-$linear optimization models.