The correct answer is option 1, which refers to the manufacture of diesel-electric submarines. The P-75 I (or P-7 5. India) project is a defense project in India that aims to build submarines for the Indian Navy.

A diesel-electric submarine is a type of submarine that is powered by diesel engines on the surface and electric batteries when submerged. These submarines are known for their capabilities in stealth operations and are commonly used for various naval missions, including surveillance, intelligence gathering, and defense.

Option 2, nuclear-powered submarines, refers to a different type of submarine that is powered by a nuclear reactor. These submarines have long endurance and can operate underwater for extended periods without the need to surface for air.

Option 3, aircraft carrier warships, refers to large warships that are designed to carry and operate military aircraft. These aircraft carriers typically have a flight deck and hangar for aircraft operations.

Option 4, field guns, refers to artillery guns that are designed for use in the field by ground forces. These guns are often towed by vehicles or transported by helicopters for mobility during combat operations.

In summary, the P-75 I project in India is focused on the manufacture of diesel-electric submarines, which are