An allegory is a story that uses characters and settings as symbols that carry a deeper meaning beyond the obvious meaning of the story. Which excerpt from Nathaniel Hawthorne’s "Dr. Heidegger's Experiment" best reveals the allegorical nature of this short story?

a) A strange chillness, whether of the body or spirit they could not tell, was creeping gradually over them all. They gazed at one another, and fancied that each fleeting moment snatched away a charm.
b) But the doctor's four friends had taught no such lesson to themselves. They resolved forthwith to make a pilgrimage to Florida, and quaff at morning, noon, and night, from the Fountain of Youth.
c) Then all shouted mirthfully, and leaped about the room. The Widow Wycherly—if so fresh a damsel could be called a widow—tripped up to the doctor's chair, with a mischievous merriment in her rosy face.
d) With a shuddering impulse, that showed her a woman still, the widow clasped her skinny hands before her face, and wished that the coffin-lid were over it, since it could be no longer beautiful.