List Comprehension in C# with LINQ - part 2

In this example, I tried to figure how to use
a static method to filter an array

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace LINQArray
{
    class Program
    {
        public static bool filter(string s)
        {
            bool ret = false;
            if (s.StartsWith("A"))
            {
                ret = true;
            }
            return ret;
        }

        static void Main(string[] args)
        {
            string[] countries = { "Britain", "France", "Croatia", "Argentina", "Australia", "Mexico", "Finland", 
                                     "Spain", "Italy", "Greece" };
            var thecountries = from c in countries
                               where filter(c)                    
                               select c;
            foreach (var c in thecountries)
            {
                Console.WriteLine(c);
            }
            Console.ReadLine();
        }
    }
}