Answer: B. Dramatic irony.
Step-by-step explanation: An irony is a statement or situation that seems contradictory or different to what the audience is expecting. A dramatic irony is a situation where the audience understand what is happening but the characters don't, which usually leads to a contradictory situation. In "The Story of an Hour” we can see a clear example of a dramatic irony, where the readers know that seeing her husband was a great disappointment for Mrs. Mallard, but the doctors think that she died of joy.