A federal statute requires United States civil service employees to retire at age 75. However, that statute also states that civil service employees of the armed forces must retire at age 65. The plaintiff, a 65-year-old service employee of the Department of the Army, seeks a declaratory judgment that would forbid his mandatory retirement until age 75. The strongest argument that the plaintiff can make to invalidate the requirement that he retire at age 65 is that the law: Question 9 options: a) denies him a privilege or immunity of national citizenship. b) deprives him of a property right without just compensation. c) is not within the scope of any of the enumerated powers of Congress in Article I, Section 8. d) invidiously discriminates against him on the basis of age in violation of the Fifth Amendment