Dual Federalism Is a Term Used to Describe a Circumstance

Dual federalism is a term used to describe a circumstance in which

A) national and state governments are sovereign and equal within their constitutionally allocated spheres of authority.
B) the state governments, having called the original Constitutional Convention, may agree to nullify federal acts.
C) the term nation-centered federalism best describes the allocation of authority.
D) the metaphor of a marble cake best represents the relationship between levels of government.