What Was the IAEA Additional Protocol

What was the IAEA Additional Protocol?

A) A multilateral agreement among NPT members to give the IAEA authority to monitor the nuclear stockpiles of nuclear weapons states, including the U.S.
B) A voluntary agreement negotiated with NPT members that granted the agency authority to visit any location where nuclear materials might be present.
C) A multilateral agreement among NPT members giving the P5+1 authority to aid the IAEA investigate Iran's nuclear weapons program.
D) An IAEA ruling that North Korea was in violation of the Nuclear Nonproliferation Treaty.