Return drop download URL from VSO Rest API

So I am able to pull in a bunch of build info by running the code below.  What code do I need to add to pull the drop download URL from the result?

using (HttpResponseMessage response = client.GetAsync(
                                "https://{accountname}.visualstudio.com/DefaultCollection/_apis/build/builds/{buildid}?api-version=1.0-preview.1").Result)
                    {
                        response.EnsureSuccessStatusCode();                     


                        string responseBody = await response.Content.ReadAsStringAsync();
                        Console.WriteLine(responseBody);

}