Moment of inertia is the

A. if any number of forces acting at a point can be represented by the sides
of a polygon taken in order, then the forces are in equilibrium
B. if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon, then the forces are in equilibrium
C. if a polygon representing forces acting at a point is closed then forces are in equilibrium
D. if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon taken in order, then the forces are in equilibrium
E. none of the above.

A. ellipse
B. hyperbola
C. parabola
D. circle
E. none of the above