x and y are positive integers. If x is a prime factor of y^2 , which of the following MUST be true?
Choose the correct choice from the following:
A) x is even
B) x=y^2
C) y/x is even
D) x/y <=1
E) x+1 is also the prime factor of y^2
A. x is even --&gt; not necessarily true: x=3=odd and y=3   B. x=y2--&gt; never true, as x=primex=prime then it can not equal to square of another integer;   C. yx is even --&gt; not necessarily true: if x=3x=3 and y=3y=3 then yx=1=odd   D. xy≤1 is less than or equal to 1 --&gt; always true as shown above or by POE;   E. x+1 is also a prime factor of y2--&gt; not necessarily true: if x=2 and y=2 then x+1=3 and 3 is not a factor of y2=4   Answer: x/y &lt;=1.
<result>D</result>
x and y are positive integers. If x is a prime factor of y^2 , which of the following MUST be true?