Which one of the following engines will have heavier flywheel than the remaining ones?

• A. 30 kW four-stroke petrol engine running at 1500 r.p.m.
• B. 30 kW two-stroke petrol engine running at 1500 r.p.m.
• C. 30 kW two-stroke diesel engine running at 750 r.p.m.
• D. 30 kW four-stroke diesel engine running at 750 r.p.m.