Provide the ID of the most popular platform in Europe.
ID refers to game_platform_id; the most popular refers to max(num_sales); in Europe refers to region_name = 'Europe'
SELECT T.game_platform_id FROM ( SELECT T1.game_platform_id, SUM(T1.num_sales) FROM region_sales AS T1 INNER JOIN region AS T2 ON T1.region_id = T2.id WHERE T2.region_name = 'Europe' GROUP BY T1.game_platform_id ORDER BY SUM(T1.num_sales) DESC LIMIT 1 ) t
database name:db_id video_games
genre table genre Cols: id dtype integer, genre_name dtype text, 
game table game Cols: id dtype integer, genre id dtype integer, game name dtype text, 
platform table platform Cols: id dtype integer, platform_name dtype text, 
publisher table publisher Cols: id dtype integer, publisher_name dtype text, 
game_publisher table game_publisher Cols: id dtype integer, game id dtype integer, publisher id dtype integer, 
game_platform table game_platform Cols: id dtype integer, game publisher id dtype integer, platform id dtype integer, release year dtype integer, 
region table region Cols: id dtype integer, region_name dtype text, 
region_sales table region_sales Cols: region_id dtype integer, game platform id dtype integer, number sales dtype real, 
