Explanation:

- In India, the informal sector typically refers to establishments that are not registered with the government and usually hire less than 10 workers.

- Establishments with four hired workers usually fall under the informal sector, because formal sector establishments are those with 10 or more workers and/or are registered with the government.

- Option 1 (Informal) is correct for a business with four hired workers.

- Option 2 (Formal) is incorrect; formal sector criteria are not met.

- Option 3 (Both) is incorrect; it can’t be both at the same time.

- Option 4 (None) is also incorrect; it is classified as informal.

Option 1: Informal is the right answer.