Explanation:

- Option 1: Punjab

Punjab has a significant dairy industry, but it's not primarily known for its milk cooperatives to the extent Gujarat is.

- Option 2: Gujarat

Gujarat is famous for the success story of the Amul cooperative and the White Revolution. It is a prime example of efficient milk cooperative management.

- Option 3: Uttar Pradesh

Uttar Pradesh has a large dairy industry, but it isn't highlighted for innovative milk cooperative models like Gujarat.

- Option 4: West Bengal

West Bengal is not known predominantly for dairy cooperatives on a national scale.

Answer: Option 2 - Gujarat

Gujarat is renowned for its pioneering work in milk cooperatives, led by Amul. It’s often cited as a successful model.