If r_{1}, r_{2}, r_{3} are the radii of the escribed circles of a triangle ABC and r is the radius of its in-circle then the root(s) of the equation x_{2} – r (r_{1}r_{2} + r_{2}r_{3} + r_{3}r_{1})x + r_{1}r_{2}r_{3} – 1 = 0 is/are

(A) 1

(B) r_{1} + r_{2} + r_{3}

(C) r

(D) r_{1}r_{2}r_{3} – 1