\(x\) and \(y\) are positive integers. If \(x\) is a prime factor of \(y^2,\) which of the following MUST be true?

[Vincen]

\(x\) and \(y\) are positive integers. If \(x\) is a prime factor of \(y^2,\) which of the following MUST be true?

A. \(x\) is even
B. \(x=y^2\)
C. \(\dfrac{x}{y}\) is even
D. \(\dfrac{x}{y} \le1\)
E. \(x+1\) is also the prime factor of \(y^2\)

Answer: D

Source: GMAT Club Tests