What was the original purpose of the Foreign Intelligence Surveillance Act?

[answerhappygod]

What was the original purpose of the Foreign Intelligence Surveillance Act?

A. To further define what information can reasonably be under surveillance in public places under the USA PATRIOT Act, such as Internet access in public libraries.
B. To further clarify a reasonable expectation of privacy stemming from the Katz v. United States decision.
C. To further define a framework for authorizing wiretaps by the executive branch for national security purposes under Article II of the Constitution.
D. To further clarify when a warrant is not required for a wiretap performed internally by the telephone company outside the suspect’s home, stemming from the Olmstead v. United States decision.