using System;

using System.Collections.Specialized;                   

public class Program

{

    public static void Main()

    {

        NameValueCollection eventData=new NameValueCollection();           

        eventData.Add("test","s");

        bool optOutOfMarketingMessages = (eventData["test"]?.Trim().Equals("S", StringComparison.OrdinalIgnoreCase) == true);

​

        Console.WriteLine(optOutOfMarketingMessages);

    }

}