Final answer:
The excerpt from 'The Story of an Hour' illustrating irony is when Louise Mallard whispers 'Free! Body and soul free!' celebrating her freedom following her husband's death, only to die from shock when he returns alive.
Step-by-step explanation:
The excerpt from "The Story of an Hour" that best illustrates the author's use of irony is: "Free! Body and soul free!" she kept whispering. Here, Louise Mallard celebrates her newfound freedom after learning of her husband's death, relishing the thought of living for herself. The irony is stark when her husband, Brently Mallard, who was believed to be dead, returns home unharmed, leading to Louise's own death from the shock of seeing him alive. This ironic twist underscores the theme of the unpredictability of life and the consequences of freedom and repression. The final line, "When the doctors came they said she had died of heart disease--of the joy that kills," adds yet another layer of irony, suggesting that the shock of losing her freedom is what ultimately leads to her death, contrary to the doctors' belief that it was joy that killed her.