The correct answer is D.
The Story of An Hour starts with the death of her husband, Mr. Mallard. She was clearly living unhappy in her marriage, and this is why she felt relieved when her husband dies, as she was finally able to start a free life on her own. She was not trapped in a repressive relation anymore.
This helps to understand how her energy, love for life and desires to live long, take an ironic twist when she notices that Mr. Wallace is actually alive.