Which pair includes two of the five surviving Spartoi?

The correct answer identifies Chthonius and Udaeus as two of the five surviving Spartoi, which are legendary warriors from Greek mythology. The Spartoi were said to have sprung from the dragon's teeth planted by Cadmus, and they initially fought among themselves until only five remained. Chthonius and Udaeus are recognized figures among these survivors, noted for their roles in various mythological narratives.

The other options do not correctly identify two of the surviving Spartoi. For instance, while Echion is indeed one of the Spartoi, Theseus is not; he is a distinct hero of Greek mythology unrelated to the Spartoi's origin story. Similarly, Hector, a renowned Trojan prince, does not belong to this group of warriors, and while Udaeus is a Spartoi, pairing him with Hector does not reflect the mythological context of the Spartoi. Thus, the choice of Chthonius and Udaeus accurately reflects their status within the mythological tradition.