According to “The Wife of Bath’s Tale,” why does the knight agree to marry the old woman?

He thinks the queen will not have him killed if he is married.
She deceived him with magic, making him think she was beautiful.
She promises him that she knows the secret to what all women want.
She tells him she will take his material possessions if he does not marry her.

The correct answer is:

She promises him that she knows the secret to what all women want.

According to "The Wife of Bath's Tale," the knight agrees to marry the old woman because she promises him that she knows the secret to what all women want.