98.
The answer is: D
Explanation
The correct option is D: (a) and (b).
Procedural ultra vires means that a subordinate legislation fails to comply with certain procedural requirements prescribed by the parent act or by the general law. The parent act or enabling statute may require the delegate to observe a prescribed procedure while framing subordinate legislation. If the delegate does not follow the procedure, the subordinate legislation may be challenged and declared invalid or void.