<p>It is vital to implement a <strong>(A) regulation</strong> on limiting operating costs in order to overcome the company's financial difficulties.</p>
<p>The correct answer is <strong>(A) regulation</strong>.</p>
<p>In this sentence, the word "implement" suggests that the company needs to put a specific rule or guideline in place to limit their operating costs. This indicates that a noun is needed to represent the rule or guideline.</p>
<p>Option (A) "regulation" is a noun that refers to an official rule or guideline that is set by an authority or governing body. This noun fits well in the context of the sentence, as it suggests the need for a specific rule to be implemented.</p>
<p>Options (B) "regulate" and (C) "regulatory" are both verb forms. They do not fit grammatically in the sentence because they represent the action of controlling or managing operating costs, rather than the rule itself.</p>
<p>Option (D) "relatively" is an adverb that means to a certain extent or in comparison to something else. It does not fit the context of the sentence, as it does not convey the idea of a rule or guideline to limit operating costs.</p>