I wish to know whether it is possible make static field non-static and provide appropriate object to calling property. Problem is highlighted.
 
using System;
using System.Collections;
public class Person : IComparable
{
    public enum SortMethod
    { Firstname = 0, Lastname = 1, Age = 2 };
    private string firstname;
    private string lastname;
    private int age;
    private static SortMethod sortOrder;
    public static SortMethod SortOrder
    {
        get { return sortOrder; }
        set { sortOrder = value; }
    }
    public string Firstname
    {
        get { return firstname; }
        set { firstname = value; }
    }
    public string Lastname
    {
        get { return lastname; }
        set { lastname = value; }
    }
    public int Age
    {
        get { return age; }
        set { age = value; }
    }
    public Person(string firstname, string lastname, int age)
    {
        this.firstname = firstname;
        this.lastname = lastname;
        this.age = age;
    }
    public override string ToString()
    {
        return String.Format("{0} {1}, Age = {2}", firstname, lastname, age.ToString());
    }
    public int CompareTo(object obj)
    {
        if (obj is Person)
        {
            Person p2 = (Person)obj;
            switch (sortOrder)
            {
                case SortMethod.Lastname:
                    return lastname.CompareTo(p2.Lastname);
                case SortMethod.Age:
                    return age.CompareTo(p2.Age);
                case SortMethod.Firstname:
                default:
                    return firstname.CompareTo(p2.Firstname);
            }
        }
        else
            throw new ArgumentException("Object is not a Person.");
    }
}
public class TestClass
{
    public static void Main()
    {
        ArrayList people = new ArrayList();
        people.Add(new Person("John", "Doe", 76));
        people.Add(new Person("Abby", "Normal", 25));
        people.Add(new Person("Jane", "Doe", 84));
        people.Sort();
        foreach (Person p in people)
            Console.WriteLine(p.ToString());
        
        Console.ReadLine();
        Person.SortOrder = Person.SortMethod.Lastname;
        people.Sort();
        foreach (Person p in people)
            Console.WriteLine(p);
        Console.ReadLine();
        Person.SortOrder = Person.SortMethod.Age;
        people.Sort(); //This is not Array.Sort(people)
        foreach (Person p in people)
            Console.WriteLine(p);
        Console.ReadLine();
    }
}