If a method is marked as protected internal who can access it?

233.

Access is limited to the current assembly

Access is limited to the containing class or types derived from the containing class.

Access is limited to the containing type

Access is limited to the current assembly or types derived from the containing class.

protected Access is limited to the containing class or types derived from the containing class.
internal Access is limited to the current assembly.
protected internal Access is limited to the current assembly or types derived from the containing class.
private Access is limited to the containing type.