Trying to call the 'Value' property of Nullable parameters vs GetValueOrDefault

Nullable_Value_vs_GetValueOrDefault

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            int? nullableInt = null;
            int? nullableInt2 = 1;
            SeeIfThisWorks(nullableInt, nullableInt2);
        }

        private static void SeeIfThisWorks(int? nullableInt, int? nullableInt2, int? notPassed = null)
        {
            var a = nullableInt.GetValueOrDefault(); //equal to 0
            var b = nullableInt2.GetValueOrDefault();
            var c = notPassed.GetValueOrDefault(); //equal to 0
            var d = nullableInt.Value; //throws error
            var e = nullableInt2.Value;
            var f = notPassed.Value;  //throws error
        }
    }
}