Explanation:

- The Anushilan Samiti was a prominent revolutionary organization in the early 20th century.

- It was particularly active in the Bengal region during the time of British India.

- Members of this group were involved in various activities aimed at gaining India’s independence.

- Option 1: Madras - Not the correct region where Anushilan Samiti was primarily active.

- Option 2: Bengal - This is the correct region where Anushilan Samiti was active. Their operations mostly took place here.

- Option 3: Punjab - Not significantly associated with Anushilan Samiti’s activities.

- Option 4: Bombay - This region was also not the main area of Anushilan Samiti's influence.