Explanation:

- The Blue Revolution is primarily associated with the development and proliferation of aquaculture and fish production.

- Option 2: Fish is correct. The Blue Revolution aims to enhance fish production to meet food demands while ensuring sustainable practices.

- Option 1: Milk is linked to the White Revolution, which focused on increasing milk production, notably led by Operation Flood in India.

- Option 3: Egg is often related to the involvement in animal husbandry but not specifically to any revolution like the Blue Revolution.

- Option 4: None of these is not relevant as this option does not apply to the Blue Revolution.