A two variable linear program has the following characteristics: The objective function maximizes $7$X$1+12$X$2$; Constraint $1$ states that X$1<=1$; constraint $2$ states that X$2<=1$; constraint $3$ states that X$1>=0$; constraint $4$ states that X$2>=0.$ Which of the following statements is true about the linear program?

Group of answer choices

The optimal solution value is $19\mathrm{.}75.$

In the optimal solution, constraint $1$ has a slack of zero and constraint $2$ has a surplus of $1.$

In the optimal solution, constraint $3$ has a slack of $0.$

In the optimal solution, constraint $1$ has $$slack variable$=0.$