According to law of triangle of forces __________________ ?

A. three forces acting at a point will be in equilibrium
B. three forces acting at a point can be represented by a triangle, each side being proportional to force
C. if three forces acting upon a patticle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium
D. if three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two
E. none of the above