Answer :
The answer is the Greek idea of excellence. The Greek idea of a human arête changed after some time. In the Iliad, an epic story rising up out of the far off Greek past, it is a term related with warriors who epitomize boldness, wildness and physical expertise. Characters like Achilles or Hector speak to an about flawless acknowledgment of mankind in a war-like, tribal society.
When Achilles becomes the best warrior he can be, what he demonstrates then is A. the Greek idea of excellence. He was very determined to become the strongest and the most agile warrior there ever was, and he succeeded in doing so, despite his flaw in the form of his heel which is the only place that he can be hurt. The Greek valued excellence quite a lot, as well as strength and warrior-spirit, so this would be an example of that.
