Which Best Describes the Difference Between Total Preemption and Partial

Which best describes the difference between total preemption and partial preemption?

A) In partial preemption,state regulatory standards need to be as least as stringent as those of the federal government.
B) In partial preemption,states can determine which regulatory standards need to match that of the federal government.
C) In partial preemption,state law in a particular field is valid as long as it does not conflict with federal law.
D) In partial preemption,state law in a particular field is valid even if the federal government has all regulatory powers in the field.