Read the excerpt below from The Call of the Wild and answer the question that follows. This first theft marked Buck as fit to survive in the hostile Northland environment. It marked his adaptability, his capacity to adjust himself to changing conditions, the lack of which would have meant swift and terrible death. It marked, further, the decay or going to pieces of his moral nature, a vain thing and a handicap in the ruthless struggle for existence.
The passage above gives the concept of morality:

positive associations
negative connotations
thematic insignificance
confusing implications

ONLY ANSWER IF YOU'RE 100% SURE THAT YOU ARE RIGHT