What is the function of the MEA on charts?

The function of the MEA on charts is to denote the Minimum Enroute Altitude. This altitude has specific significance for pilots navigating through controlled airspace. It ensures a safe vertical clearance from terrain and obstacles along the route of flight. The MEA guarantees that aircraft will remain clear of those obstacles while also providing adequate radio signal reception for navigation. This altitude is especially important for maintaining safe operations, particularly in areas with varying topography. By utilizing the MEA, pilots can effectively plan their routes, ensure safety, and comply with air traffic regulations. The other options relate to altitudes that either do not exist or serve different purposes, making them less relevant in the context of enroute navigation.