Question

How does Perseus learn the Gray Sisters' secret?

He asks them a riddle they cannot answer and forces them to tell him their
secret.
He tells them that he will slay them if they do not tell him their secret, so they
are forced to tell him.
He tells them that they look young and beautiful, and they agree to tell him their
secret.
He takes their tooth and eye and refuses to give them back unless they tell him
their secret.

Answer 1

Perseus learns the Gray Sisters' secret by taking their tooth and eye.

Step-by-step explanation:

Perseus learns the Gray Sisters' secret by taking their tooth and eye and refusing to give them back unless they tell him their secret. This act of coercion forces the Gray Sisters to reveal their secret to him.

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