Given an optimization problem z=C^T -> Max under Ax<=b, x>=0 with a non-empty allowed range Which of the following state

[answerhappygod]

Given an optimization problem
z=C^T -> Max under Ax<=b, x>=0
with a non-empty allowed range
Which of the following statements is wrong?
Choose an answer.
a) If a solution exists, the maximum is always assumed to be in a corner of the feasible region.
b)nThe allowed domain is a convex set
c) The displacement direction of the level line of the objective function is in the direction of the gradient Z.
d) The linear optimization problem has a solution.