Explanation:

- Forming a partnership deed is helpful but not mandatory for setting up a partnership. It can be established through verbal agreement or consensual partnership activities, although a written deed is advisable for clarity.

- Option 1: Mandatory

- Forming a partnership deed is not required by law, so it's not mandatory. This option is incorrect.

- Option 2: Mandatory in Writing

- While having it in writing is helpful for legal clarity, it's not legally required. This option is incorrect.

- Option 3: Not Mandatory

- This is correct. Legally, you can have a partnership without a formal deed, though it's recommended to prevent disputes.

- Option 4: None of the Above

- Given that Option 3 is correct, this option is incorrect.