Question 167Motor Plants - QMED

The correct answer is C) they are arranged to prevent gas backflow to each engine. The reason this is the correct answer is that exhaust pipes for separate main propulsion diesel engines can only be combined if they are arranged in a way that prevents the exhaust gas from one engine from flowing back into the other engine. This is a safety requirement to prevent potential damage or malfunctions that could occur if the exhaust gases were allowed to mix and flow back into the engines. The other answer choices are incorrect because: A) space limitations alone do not justify combining exhaust pipes, B) small auxiliary engines are not the focus of this question, and D) the presence of a waste heat boiler does not override the need to prevent gas backflow between the main propulsion engines.