You should check if the Community you belong to is listed in the Central OBC list and also if it falls under OBC list of Chattisgarh. . Now if you belong to OBC Category, the Category you belong to should be also listed in the Central OBC list. Or else you will be considered as General Category. Please check for your Community under the State list at: http://www.ncbc.nic.in/user_panel/centralliststateview.aspx . If it is listed here, you can select OBC or else you have to opt General Category.