The downfall of Perseus is his excessive pride. This is the reason why Polydectes is able to trick him into battling Medusa. Excessive pride is a common negative trait in Greek heroes, and it is often known as <em>hubris</em>. From this fact, we can conclude that modesty was a value that the Greeks appreciated highly.
Although A would be a good answer, the passage is more about how Sultan is "loyal to his master" and as he ws good friends with the wolf (and how the wolf did him a favor) the wolf treated it as a joke and took the sheep. Although Sultan did owe his life, that is not what is at stake with the sheep.
