In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
efg _ _ eff _ ghhe _ eff _ gggh _ h1) efgegeffhghhehefffgggheh
2) efggheffhghheheffhggghhh
3) efgheeffgghheeefffggghhh = efghe effgghh eeefffggghhh
4) efghgeffeghhefeffhgggheh
So, hegefh is required to complete this series.