List all the object classes of the images that have a (5,5) coordinate.
object classes refer to OBJ_CLASS; (5,5) coordinates refer to X and Y coordinates of the bounding box where X = 5 and Y = 5;
SELECT T2.OBJ_CLASS FROM IMG_OBJ AS T1 INNER JOIN OBJ_CLASSES AS T2 ON T1.OBJ_CLASS_ID = T2.OBJ_CLASS_ID WHERE T1.X = 5 AND T1.Y = 5