Sometimes when the state and federal governments have concurrent authority,the federal government can decide to regulate that area exclusively.In such a situation,according to the doctrine of ________,the state law is unconstitutional.

A) federal subrogation
B) federal preemption
C) federal privileges and immunities
D) res ipsa loquitur
E) stare decisis

Sometimes when the state and federal governments have concurrent authority,the federal government can decide to regulate that area exclusively.In such a situation,according to the doctrine of federal preemption,the state law is unconstitutional.
To determine whether the United States Congress intended to provide exclusive regulation,courts look to the language of the statute and transcripts of congressional hearings.