The correct answers are: the ability to embark on a challenging journey, strength and courage.
Indeed, since there is no battle in this excerpt, that particular characteristic of the epic hero convention is not met by this passage. However, the other three are quite clear; Gilgamesh and his god friend are able to complete a thousand miles travel on foot in 3 days, which means they are strong. Gilgamesh climbs to the mountain summit, which means that he is also courageous since most people would be terrified of such height. Finally, the fact that they embark on a long journey is also one of the most important parts of Epic heroic convention since epic heroes are always supposed to face an epic, initiate quest that will test his resolve and force him to face dangers and trials which he will overcome.
Answer:
The definition of indomitable is unconquerable.