Final answer:
The correct statement about executive agreements is that they are formal agreements between two countries and usually do not need congressional ratification. They are enforceable as long as they don't conflict with U.S. laws, and some may require legislative approval if financial commitments are involved. They are not obsolete but widely used in modern foreign policy.
Step-by-step explanation:
Executive agreements are formal agreements between two countries that are not ratified by a legislature as a treaty must be. They are not obsolete; rather, they are commonly used by presidents as a tool in foreign policy. Most executive agreements do not require congressional action and are considered enforceable as long as they do not conflict with domestic laws.
However, some executive agreements do require legislative approval, such as those involving financial commitments. Unlike treaties, which need a two-thirds vote in the Senate for ratification, congressional-executive agreements require a simple majority in both the House and Senate. The Supreme Court in United States v. Pink affirmed that executive agreements are legally equivalent to treaties provided they do not alter federal law.