What’s the main idea of chapter 3-4 of treasure island

Jim attends to the ailing Billy, who begs him for a swig of rum in return for some money. Jim is offended, saying he wants only what Billy owes his father for rent. But he gives Billy one glass of rum. Energized by the alcohol, Billy says he must quickly get moving to outsmart his pursuers. He explains to Jim that the former crew of the ship he sailed on, under the now-dead Captain Flint, wants his sea chest. That night Jim’s father, who has also been ill, dies.

Returning from his father’s funeral, Jim encounters a sinister blind man who asks to be taken to Billy. Billy appears sickened to see the blind man, who hands him a black spot, which Jim has learned represents an official secret pirate summons. Reading the black spot, Billy enigmatically cries out that he has only six hours left. He springs into to action, but falls down, stricken with a fatal stroke. Jim is worried and calls for his mother.

Jim tells his mother about the pirates’ plot to take Billy’s sea chest, and he flees with her to the neighboring village to seek help. Terrified by the name of old Flint, none of the villagers is willing to go to the inn to offer assistance. Armed with a gun, Jim returns with his mother to the inn. He searches through the dead Billy’s clothing to find the key to the treasure chest. Finding the key around Billy’s neck, Jim and his mother open the chest and find gold hidden at the bottom, a portion of which Jim’s mother claims as her due. They hear running footsteps in the street outside. Jim takes some papers wrapped in an oilcloth that he has found in the sea chest and then flees the inn with his mother. Weakened by fear, his mother faints outside. Jim succeeds in dragging her under a bridge, out of sight but within earshot of the inn.

Explanation:

part a.   = c.)

part b. = a.)

explanation: