Which of the film directed by director Abbas Kiarostami has the highest average score?
Abbas Kiarostami' is director_name; the highest Average score refers to Max(Avg(rating_score));
SELECT T2.movie_title FROM ratings AS T1 INNER JOIN movies AS T2 ON T1.movie_id = T2.movie_id WHERE T2.director_name = 'Abbas Kiarostami' GROUP BY T2.movie_title ORDER BY SUM(T1.rating_score) / COUNT(T1.rating_id) DESC LIMIT 1