Multi-select: Knowing that "if one electrical conductor contacts another electrical conductor then electricity will flow through both conductors", how would one answer "Electricity from a power plant lights up a light bulb in a house because"

Select from:
[1]. a conductor is unnecessary
[2]. there is only one conductor
[3]. a conductor inside the house contacts a conductor outside the house
[4]. the house is free of conductors...A:
[3].