m3 are located at the vertices of an equilateral triangle of length ‘a’ . The moment of inertia of the system about an axis along the altitude of the triangle passing through m1 is

(a)    (m2+m3)a4/4 (b)    (m 1+m2+m 3)a2 (c)    (m1+m2)a2/2 (d)    (m2+m3)a2 Ans. a (48)