Explanation:

- Robbery (Option 1):

- Robbery involves taking property with violence or intimidation.

- It requires immediate fear of harm to person or property.

- Dacoity (Option 2):

- This is like robbery but carried out by a group of five or more.

- It involves violence and is generally more organized.

- Theft (Option 3):

- Theft involves taking someone's property without consent.

- It does not involve deception or force in acquiring a signature.

- Extortion (Option 4):

- Extortion involves inducing someone to deliver something, typically by using force or threats.

- In this case, A uses the threat of grievous hurt to get Z to sign the paper, making this extortion.

Answer: Extortion (Option 4)