Answer:
C. The Water of Youth possessed merely a virtue more transient than that of wine.
F. 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.
Step-by-step explanation:
Nathaniel Hawthorne's "Dr. Heidegger's Experiment" revolves around the scientific experiment of a doctor about "the Fountain of Youth" by using his four friends as his test subjects. And as they grow younger with the water, they became more greedy and foolish, reverting to their selves when they were young.
The theme of longevity and the desire to be young, along with the foolishness of man that arises out of the pessimistic view of one's nature are represented in this story. And the sentences that best reflect the theme are sentences C and F. These two sentences present how the doctor views the water of Youth to be, "more transient than that of wine". Its effects stayed momentarily and couldn't give them permanent or long-lasting happiness/ youth. But despite their re-discovering of the foolishness and greed that their 'youth' brings, the friends still resolved to take a pilgrimage to Florida and bask in the water "morning, noon and night".