Because we are dealing with integers, C# division or modulus by zero already throws a DivideByZeroException. There's no need to explicitly build and throw one. If we were using floats or doubles, we would get one of the infinities (or in the case of 0.0 / 0.0 or 0.0 % 0.0, NaN) as a result and would need to do further work to handle that.

public static void Main(string[] args)
{
Activity workflow1 = new Workflow1();
WorkflowInvoker.Invoke(workflow1);

        Console.WriteLine ("hello world");
        // return "hello world|":
        // Gravità	Codice	Descrizione	Progetto	File	Riga	Stato eliminazione
        // Avviso	CS0028	'Program.Main()' non può essere un punto di ingresso 
        // perché la firma è errata	Codewars-Csharp	C:\Users\giaco\source\repos\Codewars\codewars-cs\Codewars-Csharp\1-HelloWorld.cs	57	Attivo

        // i fixed C# include all versions
    }

For c# this solution actually includes the dividebyZeroException that was asked