In Class 4-C shall be placed any registrant who:

(a) Establishes that he is a national of the United States and of a country with which the United States has a treaty or agreement that provides that such person is exempt from liability for military service in the United States.

(b) Is an alien and who has departed from the United States prior to being issued an order to report for induction or alternative service that has not been canceled. If any registrant who is classified in Class 4-C pursuant to this paragraph returns to the United States he shall be classified anew.

(c) Is an alien and who has registered at a time when he was required by the Selective Service Law to present himself for and submit to registration and thereafter has acquired status within one of the groups of persons exempt from registration.

(d) Is an alien lawfully admitted for permanent residence as defined in paragraph (2) of section 101(a) of the Immigration and Nationality Act, as amended (66 Stat. 163, 8 U.S.C. 1101), and who by reason of occupational status is subject to adjustment to nonimmigrant status under paragraph (15)(A), (15)(E), or (15)(G) or section 101(a) but who executes a waiver in accordance with section 247(b) of that Act of all rights, privileges, exemptions, and immunities which would otherwise accrue to him as a result of that occupational status. A registrant placed in Class 4-C under the authority of this paragraph shall be retained in Class 4-C only for so long as such occupational status continues.

(e) Is an alien and who has not resided in the United States for one year, including any period of time before his registration. When such a registrant has been within the United States for two or more periods and the total of such period equals one year, he shall be deemed to have resided in the United States for one year. In computing the length of such periods, any portion of one day shall be counted as a day.