You are in a stationary elevator, so that the contact force exerted by the floor on you is equal in magnitude to the force of gravity exerted on you. When the elevator starts downward, which force changes

Transfer of electrons. hope it !

If its history of, then b) because a) implies only present day (now)

In atoms, the electron carries a negative elementary or unit charge; the proton carries a positive charge. the two types of charge are equal and opposite. in an atom of matter, an electrical charge occurs whenever the number of protons in the nucleus differs from the number of electrons surrounding that nucleus.