The correct answer identifies that states cannot regulate military munitions under "traditional" (pre-MR) CERCLA. This is because the Military Munitions Rule (MMR) establishes specific guidelines and standards for the management of military munitions, therefore overriding and specifying how military munitions should be regulated. The MMR essentially creates a framework that recognizes military munitions as a unique category that requires specific regulations that differ from general hazardous substance regulations under CERCLA. In the context of the options provided, it's important to note that the other responses reflect the permissible actions of states. States are allowed to enforce stricter regulations than federal standards, as well as choose not to regulate military munitions at all if they believe it is unnecessary. Additionally, states can implement their own versions of the Munitions Rule, which aligns with the intention of the MMR to allow for state flexibility while also ensuring proper management of military munitions. Thus, the foundational principles of the Munitions Rule clarify the limitations on the regulatory authority of states regarding military munitions under traditional CERCLA.