Evaluate: Do the repeated warnings from the town's people to Atticus and his children about Bob Ewell's plans for vengeance heighten or weaken the narrative impact of the scene of his attack on Scout and Jem?
Heighten the impact of the attack — because of the strong, steady level of gruesome suspense they build.
Heighten the impact of the attack — because of the unforeseeable way in which the attack unfolds.
Weaken the impact of the attack — because they make it absolutely clear the Finches will be harmed eventually.
Weaken the impact of the attack — because the repetitiveness makes it seem unlikely the event will ever occur.
Neither heighten nor weaken the impact of the attack; they do not affect its narrative position or power.