Question :- 

Let p, q and s integers such that p2 = sq2. Then it follows that

a)   p is an even number;               b)         s is a perfect square;
c)   s divides p;                                 d)         q
2 divides p.  


Since p2 and q2 are perfect square, so ‘s’ must also be a perfect square.  

Ans: b)        s is a perfect square;