An alien enemy may be naturalized as a citizen of the United States under section 331 of the Act if:
(a) The alien's application for naturalization is pending at the beginning of the state of war, or the Service has granted the alien an exception from the classification as an alien enemy after conducting an investigation in accordance with § 331.3;
(b) The alien's loyalty to the United States is fully established upon investigation by the Service in accordance with § 331.3; and
(c) The alien is otherwise entitled to admission to citizenship.