If j and k are integers and j^2 / k is odd, which of the following must be true ?

Given: $j$ and $k$ are integers and $\frac{j^2}{k}=odd$ --> $j^2=k*odd$

(A) j and k are both even: not necessarily true, for example $j=1$ and $k=1$;
(B) j = k: not necessarily true, for example $j=3$ and $k=1$;
(C) If j is even, k is even: as $j^2=k*odd$ then in order $j$ to be even $k$ must be even too, so this statement must be true;
(D) j is divisible by k: not necessarily true, for example $j=3$ and $k=9$;
(E) j^2 > k: not necessarily true, for example $j=1$ and $k=1$.

Answer: C.