If sin(θ)=x\sin(\theta) = xsin(θ)=x and cos(θ)=y\cos(\theta) = ycos(θ)=y, which of the following expressions is identically equal to sin(4θ)\sin(4\theta)sin(4θ)?
4xy(y2−x2)4xy(y^2-x^2)4xy(y2−x2)
2xy(x2−y2)2xy(x^2-y^2)2xy(x2−y2)
4x2y24x^2y^24x2y2
x4−y4x^4-y^4x4−y4