You are given the following tableau for a maximization problem. Give conditions on the unknowns $a_1,a_2,a_3,b$ and $c$ that make the following statements true:

a$.$ The current solution is optimal.

b$.$ The current solution is optimal, and there are alternative optimal solutions.

c$.$ The current basic solution is not a basic feasible solution.

d$.$ The current basic solution is a degenerate basic feasible solution.

e$.$ The current basic solution is feasible, but the LP is unbounded.

f$.$ The current basic solution is feasible, but the objective function value can be improved by replacing $x_5$ as a basic variable with $x_1.$

$\backslash$table$[[z,x_1,x_2,x_3,x_4,x_5,$RHS$],[1,-c,2,0,0,0,10],[0,-1,a_1,1,0,0,4],[0,a_2,-4,0,1,0,1],[0,a_3,3,0,0,1,b$