Answer:
They have mobile charged particles.
Step-by-step explanation:
Plasma refers to very hot matter such that the electrons in matter are ripped away from the atoms leading to the formation of an ionized gas.
We know that the carriers of electricity are charged particles. Any state of matter that has an abundance of charge carriers will definitely be a good conductor of electricity.
Therefore, plasmas are good conductors of electricity because they have a lot of mobile charged particles.