; (ii) the State in which the endangerment may occur; and (iii) the person that is alleged to be contributing to the use of the perfluoroalkyl or polyfluoroalkyl substance causing the endangerment. (B) No action if suit is ongoing No action may be commenced under subsection (a)(1)(B) if the Administrator, in order to restrain or abate acts or conditions that may have contributed or are contributing to the activities which may present the alleged endangerment, has commenced and is diligently acting on an authority provided under an applicable law. (C) Intervention as matter of right In an action under brought under subsection (a)(1)(B) in a court of the United States, any person may intervene as a matter of right. (D) Notice of action A person bringing an action under subsection (a)(1)(B) in a court of the United States shall serve a copy of the complaint on— (i) the Attorney General