Infeasibility (no feasbile soln) and unboundedness (unbounded soln) surely require reformulation of the problem . Only Alternate optimality does not require reformulation as one soln is already there
An alternate optimal solution is also called as an alternate optima, which is when a linear / integer programming problem has more than one optimal solution. Typically, an optimal solution is a solution to a problem which satisfies the set of constraints of the problem and the objective function which is to maximize or minimize.
Hence ans is A