Which of the Following Statements Is True of Concurrent Authority

Which of the following statements is true of concurrent authority?

A) This situation arises when authority to regulate in an area has been expressly given to the state government by the Constitution.
B) When the state law is more restrictive, such that compliance with the state law is automatically compliance with the federal law, the state law will usually be valid.
C) A state can regulate in an area even if the regulation conflicts with the federal regulation of the same subject matter.
D) In many areas of environmental regulation, states may impose less stringent pollution-control standards than those imposed by federal law.