Final answer:
Mrs. Mallard in 'The Story of an Hour' suffers from heart trouble, which is vital to the story as it reflects both her physical condition and the emotional constraints she faces.
Step-by-step explanation:
From what ailment does Mrs. Mallard suffer? Mrs. Mallard, a character in Kate Chopin's "The Story of an Hour," suffers from heart trouble. This ailment is significant as it underlines the character's fragile state and the care that others around her feel they must take in communicating any shocking news, such as the death of her husband. The significance of her heart trouble is not merely a physical condition, but it also symbolizes the emotional and psychological constraints imposed on Mrs. Mallard by her marriage and the society at the time. When Mrs. Mallard learns of her husband's death, she experiences a complex mixture of emotions, including a sense of freedom which the author depicts as both liberating and overwhelming for her frail heart.