What is the proper way to re-throw an exception in C#? [duplicate]

Answer 1

I found that if the exception is thrown in the same method that it is caught, the stack trace is not preserved, for what it's worth.

void testExceptionHandling()
{
    try
    {
        throw new ArithmeticException("illegal expression");
    }
    catch (Exception ex)
    {
        throw;
    }
    finally
    {
        System.Diagnostics.Debug.WriteLine("finally called.");
    }
}