There are 2 options for it:
1. HTML parsing
You need to get the HTML code, then process it to find the signiture of the so called "top results".
You can use code like this example to get the HTML code:
string urlAddress = "https://www.google.co.il/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=what%20is%20the%20weight%20of%20human%20heart";
// need to process to get the real URL of the question.
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(urlAddress);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
if (response.StatusCode == HttpStatusCode.OK)
{
Stream receiveStream = response.GetResponseStream();
StreamReader readStream = null;
if (response.CharacterSet == null)
{
readStream = new StreamReader(receiveStream);
}
else
{
readStream = new StreamReader(receiveStream,Encoding.GetEncoding(response.CharacterSet));
}
string data = readStream.ReadToEnd();
response.Close();
readStream.Close();
}
This will give you the returned HTML code from the website.
To extract of the top result you can use some HTML parser like discussed here: What is the best way to parse html in C#?
2. GOOGLE API
You can also use the google API:
using Google.API.Search;
and then
var client = new GwebSearchClient("http://www.google.com");
var results = client.Search("google api for .NET", 100);
foreach (var webResult in results)
{
//Console.WriteLine("{0}, {1}, {2}", webResult.Title, webResult.Url, webResult.Content);
listBox1.Items.Add(webResult.ToString ());
}