Answer: He causes the birth of a hero in Troezen.
Step-by-step explanation:
King Aegeus’s actions affected the advancement of the plot by causing the birth of a hero in Troezen.
In the first part of "Cruel Tribute, we were informed that King Minos wanted revenge because his son Androgeous was murdered.
He then asked the elders whether King Aegeus had a son but he got a negative reply from them even though it was true that King Aegeus had a son. Then, his son Theseus continued living in Troezen and eventually became a hero there.
Therefore, the correct option is C.