True or False?

(a) The dual of the dual problem yields the original primal.

(b) If the primal constraint is originally in equation form, the corresponding dual variable is necessarily unrestricted.

(c) If the primal constraint is of the type ≤, the corresponding dual variable will be nonnegative (nonpositive) if the primal objective is maximization (minimization).

(d) If the primal constraint is of the type ≥, the corresponding dual variable will be nonnegative (nonpositive) if the primal objective is minimization (maximization).

(e) An unrestricted primal variable will result in an equality dual constraint.