You write the following code segment to call a function from the Win32 Application Programming Interface （API） by using platform invoke.  
string personName = "N？el"； 
string msg = "Welcome " + personName + " to club ’’!"； 
bool rc = User32API.MessageBox（0， msg， personName， 0）； 
You need to define a method prototype that can best marshal the string data.
Which code segment should you use？（）