The correct answer is B) Less weight per unit of horsepower. Steam turbines are generally lighter in weight compared to diesel engines of the same horsepower output. This is because steam turbines have fewer moving parts and do not require the heavy engine block and crankshaft assembly found in diesel engines. The lighter weight of a steam turbine allows for more efficient power generation and transmission, making it advantageous for marine applications where weight is a critical factor. The other answer choices are not as accurate. Option A is incorrect because steam turbines can have higher fuel consumption compared to modern diesel engines. Option C is incorrect because steam turbine systems typically have a higher initial installation cost than diesel propulsion. Option D is incorrect because steam turbines generally have a slower response from ahead to astern compared to diesel engines.