C# compare input with keywords
<p>ive got the following c# code:</p>

<pre><code>string textBoxInput = richTextBox1.Text;
                StreamReader SentencesFile = new StreamReader(@"C:\Users\Jeroen\Desktop\School\C#\opwegmetcsharp\answersSen.txt");
                string Sentence = SentencesFile.ReadLine();
                List&lt;List&lt;string&gt;&gt; keywordsList = new List&lt;List&lt;string&gt;&gt;();
                List&lt;string&gt; outputSentence = new List&lt;string&gt;();

                while (Sentence != null)
                {
                    string keywords = Sentence.Substring(0, Sentence.IndexOf(' '));
                    string sentenceString = Sentence.Substring(0, Sentence.IndexOf(' ') +1);
                    List&lt;string&gt; splitKeyword = keywords.Split(',').ToList();
                    keywordsList.Add(splitKeyword);
                    outputSentence.Add(sentenceString);
                }
                int similar = 0;
                int totalSimilar = 0;
                List&lt;string&gt; SplitUserInput = textBoxInput.Split(' ').ToList();
</code></pre>

<p>And a .txt file which contains the following:</p>

<pre><code>car,bmw Do you own a BMW?
car,Tesla Do you own a Tesla?
new,house Did you buy a new house?
snow,outside Is it snowing outside?
internet,down Is your internet down?
</code></pre>

<p>I can't figure out how i can compare every word that a user typed in the input (richTextBox1.Text) with the keywords in the .txt file ( like car and bmw for the first sentence )
And it also has to remember the sentence that has the highest amount of "hits".
I'm really stuck and searched a lot, but somehow i can't find out how i can do this.</p>

<p>A lot of thanks in advance!</p>