What is the primary use of fuel oil?

Fuel oil is primarily used as a heavy fuel for ships. This choice is accurate because marine vessels require a type of fuel that can provide the necessary energy to operate large engines and support long-distance travel. Fuel oil, specifically marine diesel or bunker fuel, is designed to meet the demanding energy requirements of ships.

The other options do not align with the primary use of fuel oil. Lorries usually run on diesel or petrol, aeroplanes utilize aviation fuel such as Jet A-1 or Avgas, and bottled gas typically refers to LPG (liquefied petroleum gas), which is distinct from fuel oil and used for heating and cooking purposes. Thus, fuel oil stands out as the efficient energy source for ships in maritime operations.