which doesnt belong and why?

1. terence powderly . wobblies . knights of labor . social reformers

2. skilled workers . samuel gompers . miners . american federation of labor

3. rutherford b. hayes . railroad strike . pittsburgh . andrew carnegie

4. pinkertons . haymarket . homestead strike . henry frick

5. american railraod union . eugene v. debs . pullman strike . alexander berkman