The option that best explains a similarity between the national government and state governments under the U.S. Constitution is:
Both the national and state governments have their own court systems to interpret laws and settle disputes.
This is accurate because both levels of government have separate judicial systems to handle legal matters and disputes within their respective jurisdictions. The other options presented are inaccurate in the context of federalism defined by the U.S. Constitution. For example, only the national government has the power to regulate foreign trade and enter into treaties, while amending the Constitution requires a process that involves both state and national government participation.