If $A+B$ means $A$ is the brother of $B$; $A\times B$ means $A$ is the father of $B$ and $A-B$ means $A$ is the sister of $B$, which of the following relations shows that $I$ is the niece of $K$?

Let's analyze Option C: $K+Y\times I-Z$
* $K+Y⟹K$ is the brother of $Y$.
* $Y\times I⟹Y$ is the father of $I$.
* $I-Z⟹I$ is the sister of $Z$ (confirming $I$ is female).

Since $Y$ is the father of $I$, and $K$ is the brother of $Y$, $K$ is the paternal uncle of $I$. Consequently, $I$ is the niece of $K$.