would achieve the relevant statutory objectives only if the additional benefits of the more costly rule justify its additional costs and only if the agency explains its reason for doing so based on interests of public health, safety or welfare that are clearly within the scope of the statutory provision authorizing the rule. (4) When it adopts a final rule, the agency shall publish a notice of final rule making. The notice shall include— (A) a concise, general statement of the rule’s basis and purpose