article VI of the US Constitution establishes that federal law is supreme in conflicts between federal and state law
the answer could be written multiple ways but the important thing to know is that the Constitution is considered the supreme law of the land meaning that if state laws conflict with federal law, federal law wins because it has the higher and more powerful authority. the conflicting state law will have no force.
C. states can rely on the federal government to protect them if needed (a p e x)
Explanation: this is correct if your answer choices are: A. all citizens are equal, no matter what their state of residence, B. in an area of conflict, federal law overrules state law, C. states can rely on the federal government to protect them if needed, and D. all powers are explicitly mentioned in the Constitution belong to the states.
I'm not sure of the exact word you are looking for, but the general idea is that the federal law will always reign supreme if there is ever a conflict between the federal and state laws. Federal law is superior or higher-ranking or more preferable, etc.
Here is the exact phrasing from Article VI of the US Constitution: "This Constitution, and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the Constitution or laws of any State to the contrary notwithstanding."
Article Six of the United States Constitution builds up the laws and arrangements of the United States made as per it as the supreme law that must be adhered to, denies a religious test as a necessity for holding a legislative position and holds the United States under the Constitution in charge of obligations acquired by the United States under the Articles of Confederation.