Extract sentences with keyword (Exercise)

using System;
using System.Linq;

namespace ConsoleTests
{
    class ConsoleTests
    {
        static void Main()
        {
            string input = Console.ReadLine();
            string wordSearched = Console.ReadLine();
            Extract(input, wordSearched);

        }

        public static void Extract(string str, string keyword)
        {
            string[] arr = str.Split('.');
            string answer = string.Empty;

            foreach(string sentence in arr)
            {
                string[] words = sentence.Split(new char[] { ' ', ',' });
                if(words.Contains(keyword,StringComparer.CurrentCultureIgnoreCase))
                {
                    Console.WriteLine(sentence.Trim()+'.');
                }
            }
        }
    }
}