Why is Achilles vulnerable at his heel?

• A. He was not dipped in the River Styx
• B. His mother held him by the heel when she dipped him in the River Styx
• C. He died of a natural disease
• D. He was struck in the head by a stone

Answer: (B)

The idea being tested is why one part of Achilles’ body stayed vulnerable even though he was made almost invulnerable. In the myth, his mother Thetis dipped him in the River Styx to grant invulnerability, but she held him by the heel during the dunk. That grip meant the water never touched that spot, so the heel remained unprotected and human flesh could be harmed there.

So the heel becomes his weak point, explaining why that small area is vulnerable. Other options don’t fit the story, since he was dipped in the river, and the vulnerability isn’t due to a natural disease or a head injury. The term “Achilles’ heel” later lives on as a common way to describe a single critical weakness.