The legislature of the state of Chetopah enacted a statute requiring that all law enforcement officers in that state be citizens of the United States. Alien, lawfully admitted to permanent residency five years before the enactment of this statute, sought employment as a forensic pathologist in the Chetopah coroner's office. He was denied such a job solely because he was not a citizen. Alien thereupon brought suit in federal district court against appropriate Chetopah officials seeking to invalidate this citizenship requirement on federal constitutional grounds. The strongest ground upon which to attack this citizenship requirement is that it 
constitutes an ex post facto law as to previously admitted aliens. deprives an alien of a fundamental right to employment without the due process of law guaranteed by the Fourteenth of law guaranteed by the Fourteenth Amendment. denies an alien a right to employment in violation of the privileges and immunities clause of the Fourteenth Amendment. denies an alien the equal protection of the laws guaranteed by the Fourteenth Amendment.
Question: The legislature of the state of Chetopah enacted a statute requiring that all law enforcement officers in that state be citizens of the United States. Alien, lawfully admitted to permanent residency five years before the enactment of this statute, sought employment as a forensic pathologist in the Chetopah coroner's office. He was denied such a job solely because he was not a citizen. Alien thereupon brought suit in federal district court against appropriate Chetopah officials seeking to invalidate this citizenship requirement on federal constitutional grounds. The strongest ground upon which to attack this citizenship requirement is that it 
A. constitutes an ex post facto law as to previously admitted aliens.
B. deprives an alien of a fundamental right to employment without the due process of law guaranteed by the Fourteenth of law guaranteed by the Fourteenth Amendment.
C. denies an alien a right to employment in violation of the privileges and immunities clause of the Fourteenth Amendment.
D. denies an alien the equal protection of the laws guaranteed by the Fourteenth Amendment.
Answer: