Explanation:

Only statements 1&2 are correct.

Air-Independent Propulsion (AIP) System

• AIP is the marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen.

• The technology create energy by combining hydrogen and oxygen, with only water created as a by-product.

• Since these cells are extremely efficient and have minimal moving parts, they can also operate without increasing the acoustic signature of the submarine.

• Hydrogen fuel cells create no exhaust fumes which also eliminates the need to have special exhaust scrubbing and disposable machine parts.

• Fuel-cell based AIPs enable submarines to stay underwater for vastly longer periods of time than conventional diesel-electric submarines increasing their range and turning them into a far more potent and lethal adversary.

• Despite the advantage it offers them against conventional diesel-electric submarines, they still do not have the same endurance as nuclear submarines that do not need to surface at all.

Hence option 1st is correct.