The answer is: D
Explanation
The most accurate application of the principle is:
D: The rule would not be invalid even if it is wrongly stated to be framed under a particular provision of the Act, provided that the rule otherwise falls within the competence of the rule-making authority.
Explanation :
The principle states that if a rule is wrongly stated to be framed under a particular provision of a statute but still falls within the competence of the rule-making authority, the wrong labeling does not render the rule ultra vires (beyond the authority). In this scenario, Rule 5 is claimed to derive its authority from section 57 of the delegating Act, even though the Act only has 55 sections.
As long as Rule 5 falls within the competence of the rule-making authority, it would not be considered invalid solely because it is wrongly labeled or stated to be framed under a specific provision that does not exist in the Act. Therefore, Option D is the most accurate application of the principle.