using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var p = new[] { new PPP()};

        foreach(var i in p.SelectMany(x => x.Groups, (x,y) => x)) {

            Console.WriteLine(i);

        }

    }

}

​

class PPP {

    public string[] Groups = new string[] {"A","B","C"};

    public string Name = "Bob";

}