Correct Option: B

	x	=	y	=	z	= k
	(b - c)(b + c - 2a)		(c - a)(c + a - 2b)		(a - b)(a + b - 2c)

∴ x = k (b – c) (b + c – 2a) = k{b² – c² – 2a(b – c)}
y = k (c – a) (c + a – 2b) = k{c² – a² – 2b(c – a)}
z = k (a – b) (a + b – 2c) = k{a² – b² – 2c(a – b)}
∴ x + y + z = k[ b² – c² + c² – a² + a² – b² – 2 {a(b – c) + b (c – a) + c (a – b)} ]
x + y + z = 0 – 2(ab – ac + bc – ab + ac – bc) = 0