Final answer:
The character who usurped the throne from his brother Aeetes and was slain by Medea is Perses, which is related to Greek mythology.
Step-by-step explanation:
The correct answer to the question about one of Helios's children by Perse who usurped the throne of Colchis from his brother Aeetes and was then slain by Medea is a) Perses. This character is related to a mythological narrative involving gods and heroes. While Perses is not as widely known as other figures in Greek mythology, his story intertwines with that of Medea, known for her role in the tale of Jason and the Argonauts and for her sorcery. The figure you are referring to is Perses, not to be confused with the Titan Perses. In Greek mythology, Perses was a son of Helios (the sun god) and Perse, and he is associated with the kingdom of Colchis. However, the myth you describe aligns more closely with the story of Aeetes, Perses' brother, who ruled Colchis. Medea, daughter of Aeetes, played a crucial role in aiding Jason and the Argonauts. Aeetes, though not usurped by Perses, faced challenges to his throne, and Medea ultimately played a part in the events leading to her brother's demise, as she assisted Jason in obtaining the Golden Fleece.