Read the following summary of a short story:

A man puts himself in a dangerous situation to save a
stranger's life. Though he is seen as a hero, he harbors
resentment over losing his leg in the process. As years go
by, he becomes increasingly bitter and refuses the help
others so desperately want to give him. In an unexpected
twist, the man's kidneys fail, and a stranger offers to
donate one of his; however, it is too late to save the man's
life. As a final act, the man decides to donate his organs to
save others.

Which two themes most clearly interact in this story?

A. The unpredictability of fate and the dangers of regret

B. The admiration for self-preservation and pity for lost potential

C. The needs of individuals versus those of society

D. The struggle for independence within the expectations of society