Final answer:
The signal fire was not lit at the crucial moment a ship passed, which is why the boys couldn't signal for help in 'Lord of the Flies'.
Step-by-step explanation:
The boys in William Golding's novel Lord of the Flies couldn't signal the ship that Ralph spotted on the horizon because the signal fire was not lit. This is a crucial moment in the novel that underscores the consequences of the boys' actions and the conflicts arising among them, particularly regarding the importance of maintaining the fire, which is their only means to signal for rescue. Their preoccupation with hunting leads to neglecting the fire, which ultimately results in the missed opportunity for rescue when a ship passes by.