using System;

 

class SomeClass

    public string GetName(object obj)

    {

        return obj.GetType().GetProperties()[0].Name;

    }

 

class Program

    static void Main()

    {

        string testVariable = "trololo";

 

        SomeClass someClass = new SomeClass();

        string variableName = someClass.GetName(new { testVariable });

 

        Console.WriteLine(variableName);

        Console.ReadKey();

    }