For real numbers a and b, define a \$ b=(a-b)^{2}. What is (x-y)^{2} \$(y-x)^{2} ?

**Answer Choices**

A. 0

B. x^{2}+y^{2}

C. 2 x^{2}

D. 2 y^{2}

E. 4 x y

For real numbers a and b, define a \$ b=(a-b)^{2}. What is (x-y)^{2} \$(y-x)^{2} ?

**Answer Choices**

A. 0

B. x^{2}+y^{2}

C. 2 x^{2}

D. 2 y^{2}

E. 4 x y