The correct option is D (x+y+z)(z−x−y)
Given: z2−(x2+2xy+y2).
Using the identity (a+b)2=a2+2ab+b2 in the above equation we get,
z2−(x2+2xy+y2)=z2−(x+y)2 . . . (i)
Using the identity a2−b2=(a+b)(a−b) in (i) we get,
z2−(x+y)2=[z+(x+y)][z−(x+y)]
=(x+y+z)(z−x−y)