If a signer cannot sign their name due to a physical disability, how can a Notary Public proceed with a signature by mark?

• By having the signer stamp their thumbprint on the document instead of a signature.
• By attaching a special medical certificate to the notarial act.
• By having a single credible witness vouch for the signer's identity.
• By requiring two witnesses to observe the mark, with one witness writing the signer's name next to the mark.