What consequence did Cadmus face for slaying the serpent devoted to Ares?

Cadmus, the founder of Thebes, faced significant consequences following his slaying of the serpent devoted to Ares. The correct outcome was that he spawned the Spartoi, which were a group of warriors that sprang from the dragon's teeth he planted in the ground after defeating the serpent. According to myth, after Cadmus killed the serpent, he was instructed by Athena to sow its teeth in the earth, leading to the sudden emergence of the Spartoi—armed fighters who would later become crucial in the mythology surrounding Thebes.

This event emphasizes Cadmus's role in establishing Thebes and highlights the themes of legacy and the interplay between divine conflict and mortal actions. The Spartoi represented both a blessing and a potential curse for Cadmus, as they would later turn on one another, which speaks to the often turbulent nature of mythology where heroes might face unforeseen consequences for their actions.

In contrast, the other choices do not accurately reflect Cadmus's fate following the killing of the serpent. Rather, they present alternatives that do not align with the established myths surrounding Cadmus and his adventures.