Which foot is preferred by Abdou Diallo?
Abdou Diallo refers to player_name = 'Abdou Diallo'; foot is preferred refers to preferred_foot
SELECT DISTINCT t2.preferred_foot FROM Player AS t1 INNER JOIN Player_Attributes AS t2 ON t1.player_api_id = t2.player_api_id WHERE t1.player_name = 'Abdou Diallo'