I'd say base
EDIT see:
http://www.c-sharpcorner.com/UploadFile/rajeshvs/ConsNDestructorsInCS11122005010300AM/ConsNDestructorsInCS.aspx
there it says:
using System;
class Base
{
public Base()
{
Console.WriteLine("BASE 1");
}
public Base(int x)
{
Console.WriteLine("BASE 2");
}
}
class Derived : Base
{
public Derived():base(10)
{
Console.WriteLine("DERIVED CLASS");
}
}
class MyClient
{
public static void Main()
{
Derived d1 = new Derived();
}
}
This program outputs
BASE2
DERIVED CLASS