Explanation:

Statement A is incorrect- Gravity, the weakest of the four forces, is about 10^-36 times the strength of the strong force. This weakness is easily demonstrable - on a dry day, when we rub a comb across shirt to give it static electricity and when we hold it over a piece of paper on a desk the piece of paper lifts off the desk. It takes an entire planet to keep the paper on the desk, but this force is easily overcome with everyday materials employing the electromagnetic force.

Statement B is correct- The magnetic field acts perpendicular to a charges instantaneous direction of motion (at right angles to its motion). Therefore if a charge is not moving, there is no perpendicular force asserted. As to why, because the magnetic field does no work (can not affect a particles speed, only direction), only electric fields exert a force. 

Statement C- Weak force, a fundamental force of nature that underlies some forms ofradioactivity, governs the decay of unstable subatomic particles such as mesons, and initiates the nuclear fusion reaction that fuels the Sun.

Statement D is correct- The nuclear force is a force that acts between the protons and neutrons of atoms.