Which of the following polynomials is the expansion of (1/2x-y)^4

Hello :

(1/2x-y)^4 = (1/2x-y)²(1/2x-y)²

but : (1/2x-y)²= (1/2)²- 2(1/2)xy +y²

so : (1/2x-y)^4 = ((1/2)²- 2(1/2)xy +y²) ((1/2)²- 2(1/2)xy +y²) =

the function makes a strait line horizontally with no x intercept but a y intercept at 9.