Answer:
a.movement
Explanation:
Electricity is defined a set of natural phenomena associated with static charges or the movement of electric charges. Whenever we are talking about electricity, we are usually referring to the transport of energy when electric charges move; therefore, whenever, there is movement of charges, there is electricity.
So, it is correct to say that electricity is the movement of charged particles.
Electricity is NOT a collection of charged particles (choice b), because stationery charges do not transport energy when left untouched; some energy transfer has to happen if we are to use the word 'electricity'.
In a similar fashion, electricity is also NOT a build up of charged particles (choice c). Although charge build up does take energy, and charges are moving, but that happens in the domain of the definition of electricity—charge build up by itself is not a definition of electricity.