What is the function of positive-crankcase ventilation?

The function of positive-crankcase ventilation (PCV) is primarily to manage the gases that escape from the combustion chamber into the crankcase. When the engine operates, combustion gases can leak past the piston rings and enter the crankcase, where they can cause pressure build-up and contamination of engine oil.

The PCV system allows these gases to be directed back into the intake manifold, where they can be reintroduced into the combustion process. As a result, this system effectively burns unburned or partially burned fuel, reducing emissions and enhancing overall engine efficiency.

This recycling of gases not only helps in improving fuel economy but also minimizes the risk of harmful emissions being released into the atmosphere. While this does relate to fuel efficiency and emissions control, the primary role of PCV is indeed about managing combustion gases, making the chosen answer correct in context.