Final answer:
Solid magenta lines on a VFR sectional chart mark the boundaries of Class E airspace that extends to the surface, which is a form of controlled airspace usually around non-towered airports.
Step-by-step explanation:
On a VFR (Visual Flight Rules) sectional chart, solid magenta lines indicate the boundaries of Class E airspace that extends to the surface, which is a type of controlled airspace. This airspace is generally around airports that do not have control towers, and different rules apply to pilots flying within this airspace compared to other types of airspace. It is designed to facilitate controlled flights while maintaining a safe environment for all aircraft operating in the vicinity.