an object that is moving must have a change in
a) its speed.
b) its position.
c) its acceleration.
d) its applied force.

B ) position

Explanation:

moving object can have a constant speed ,constant acceleration and no change in the applied force

(when there is no applied force on the object  ,it keep its motion uninterruptedly - Newton's first law of motion )

But if an object is moving , it must change its position as if it is still remain in the same position , there can never be a motion at all

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia