The main purpose of an EVAP system is to:

The primary function of an Evaporative Emission Control (EVAP) system is to capture fuel vapors that escape from the fuel system and route them to the engine. This prevents the gasoline vapors from being released into the atmosphere, thus reducing air pollution and meeting environmental regulations. When the fuel in the tank evaporates, the vapors are directed into the charcoal canister, where they are temporarily stored. Once conditions are appropriate, such as when the engine is running, the vapors are purged from the canister and delivered to the engine's intake. There, they can be combusted alongside the air-fuel mixture, thereby utilizing the vapors rather than allowing them to escape into the environment.

The other options reflect parts of the overall function of the EVAP system but do not capture the complete purpose. For instance, while the system does keep fuel vapors from escaping and temporarily stores them, the core aim is to route these vapors for combustion in the engine rather than merely preventing their release. Thus, understanding the final routing of retrieved vapors to the engine is critical for effective emission control and efficient operation of a gasoline engine.