Few properties of Primal and dual
1)The dual of dual linear programming problem is again the primal problem
2)If either the primal or dual problem has unbounded soln the other problem(dual or primal) has no feasible soln
3))If either the primal or dual problem has a finite optimal soln the other one also possesses the same and the optimal value of the objective function of 2 problems are same
so by property 2 ans is A
note :unbounded soln means there is no limit i.e away from the origin
feasible soln :- if there is some common are between lines towards origin
Unfeasible soln : if there is no common shaded area between lines
for relationship between primal and dual refer https://people.rit.edu/pnveme/EMEM820n/Mod4_LP/Mod4_content/mod4_sec5_primal_dual.html