A Massless Frame in the Shape of a Square with 2-M

Multiple Choice

A massless frame in the shape of a square with 2-m sides has a 1-kg ball at each corner.What is the moment of inertia of the four balls about an axis through the corner marked O and perpendicular to the plane of the paper?

A) 4 kg . m²
B) 8 kg. m²
C) 10 kg. m²
D) 12 kg . m²
E) 16 kg .m²