After overload resolution selects a virtual member, what selects the function body for an…

After overload resolution selects a virtual member, what selects the function body for an ordinary call through Base&?

1. The complete object's dynamic type determines the final overrider.
2. The source-file order of the class definitions determines it.
3. The static type always forces the base implementation.
4. The access level of the overriding function determines it.