The most possible answer is letter B) Liquid.
If we are going to base the answer to the motion of particles, liquid is the best answer since solid's particle cannot move for they are tightly packed while the particles of gas and plasma (ionized gas) are free and move at high speeds.
Kinetic Energy because when the pendulum is dropped its gravitational energy is transferred into kinetic energy as it gains speed.
If the force equals, for instance, 100 Newtons then 0.866 × 100 = 86.6 Newtons. This is the magnitude of the resultant force vector on the object.
