On image no. 20, identify the attribute ID that is composed of the highest number of objects.
image no. 20 refers to IMG_ID = 20; attribute ID refers to ATT_CLASS_ID; highest number of objects refers to max(count(ATT_CLASS_ID))
SELECT ATT_CLASS_ID FROM IMG_OBJ_ATT WHERE IMG_ID = 20 GROUP BY ATT_CLASS_ID ORDER BY COUNT(ATT_CLASS_ID) DESC LIMIT 1
database name:db_id image_and_language
ATT_CLASSES table ATT_CLASSES Cols: ATTRIBUTE CLASS ID dtype integer, ATTRIBUTE CLASS dtype text, 
OBJ_CLASSES table OBJ_CLASSES Cols: OBJECT CLASS ID dtype integer, OBJECT CLASS dtype text, 
IMG_OBJ table IMG_OBJ Cols: IMAGE ID dtype integer, OBJECT SAMPLE ID dtype integer, OBJECT CLASS ID dtype integer, X dtype integer, Y dtype integer, W dtype integer, H dtype integer, 
IMG_OBJ_ATT table IMG_OBJ_ATT Cols: IMAGE ID dtype integer, ATTRIBUTE CLASS ID dtype integer, OBJECT SAMPLE ID dtype integer, 
PRED_CLASSES table PRED_CLASSES Cols: PREDICTION CLASS ID dtype integer, PREDICTION CLASS dtype text, 
IMG_REL table IMG_REL Cols: IMAGE ID dtype integer, PREDICTION CLASS ID dtype integer, OBJECT1 SAMPLE ID dtype integer, OBJECT2 SAMPLE ID dtype integer, 
