Explanation:

- Option 1: Imperial system

- Refers to the governing strategy of empires.

- It involves control over vast territories and diverse populations.

- Not directly responsible for profit drain to Zamindars in Bengal.

- Option 2: Zamindari system

- A land revenue system introduced by the British in India.

- Enabled Zamindars to collect taxes from farmers and retain a portion.

- Directly responsible for shifting profits from farmers to Zamindars in Bengal.

- Option 3: Colonial system

- Involves political control over a country by a foreign power.

- Broad term that includes economic exploitations like the Zamindari system.

- Doesn't specifically point to profit drain in Bengal.

- Option 4: All of the above

- Includes all systems mentioned.

- Not all directly relate to the Bengel profit drain scenario.