When we have to connect a battery to light then we required a material that will help to conduct electricity from battery to the bulb
Here we can say that it must be a material that will always help to conduct the free charge.
Here as we know that electricity the flow of charge from one end to other
here the free charge is considered as free electrons
So the correct answer must be the material here must accept the electron flow so that on connecting them bulb will glow.
Here neutron flow is not relevant as neutron is not helpful to flow the the current
and if material will resist the flow of electrons or protons then it will resist the flow of current so it should not be the answer as well.