Read the following excerpt from levitt and dubner's freakonomics

there is a tale, "the ring of gyges," that feldman sometimes tells his economist friends. it comes from plato's
republic. a student named glaucon offered the story in response to a lesson by socrates-who, like adam smith,
argued that people are generally good even without enforcement. glaucon, like feldman's economist friends,
disagreed. he told of a shepherd named gyges who stumbled upon a secret cavern with a corpse inside that wore a
ring. when gyges put on the ring, he found that it made him invisible. with no one able to monitor his behavior,
gyges proceeded to do woeful things-seduce the queen, murder the king, and so on. glaucon's story posed a moral
question could any man resist the temptation of evil if he knew his acts could not be witnessed? glaucon seemed to
think the answer was no.

the excerpt serves as which of the following in relation to the authors' argument?

a) a claim that most people are moral
b) an example of morality in the workplace
c) a conclusion about morality in the workplace
d) a counterclaim to the idea that most people are moral