Refer to Model $5$S$\mathrm{.}4$ in your text. Also, check course slides. Which of the following is false?

A$.$ and are parameters in the model

B$.$ and are the only decision variables in the model

C$.$ If takes the value of $1$ in the optimal solution, we know that supply location $1$ is serving at least one demand location

D$.$ If takes the value of $1$ in the optimal solution, we know that demand of location is fully met by supply location $1.$

E$.$ All of the above.