((a)) An officer of the National Guard shall be discharged when—

((1)) he becomes 64 years of age; or

((2)) his Federal recognition is withdrawn.

((b)) Subject to subsection (a), the appointment of an officer of the National Guard may be terminated or vacated as provided by the laws of the State of whose National Guard he is a member, or by the laws of the Commonwealth of Puerto Rico, or the District of Columbia, Guam, or the Virgin Islands, of whose National Guard he is a member.

((c)) Notwithstanding subsection (a)(1), an officer of the National Guard serving as a chaplain, medical officer, dental officer, nurse, veterinarian, Medical Service Corps officer, or biomedical sciences officer may be retained, with the officer’s consent, until the date on which the officer becomes 68 years of age.