Answer:
Jack and Ralph struggle for power on the island.
Step-by-step explanation:
Power Struggle is a central idea in the novel. Right from the moment the boys found themselves on the island, it becomes a struggle between reasoning and instincts, democracy and dictatorship.
Ralph as an individual demonstrates good leadership skills. He is most concerned about the welfare of his subjects (the other boys), he finds ways to feed and shelter them. Those are actions of a good leader.
Jack on the other hand is a sadist and a dictator. He wants to be the boss and tries to control every other person on the island, especially the choir boys. He does not care about the little ones and is power thirsty.
Jack demonstrated his dictatorship in every way. No respect for the conch, constantly overruling Ralph's rule and turning the boys into savages.
The only saving grace on the island is the conch and the moment it got broken, law and order vanished. Jack became a true savage, killing and maiming, organising a manhunt for Ralph.
Power is very intoxicating and if placed in the hands of the wrong individual it becomes a curse to all.