第 62 题 (单选题)： Examine the description of the products table，Which query is valid.

A. SELECT prod_id, AVG(MAX (cost)) FROM products GROUP BY prod_id. B. SELECT prod_id, MAX (AVG (cost)) FROM products GROUP BY prod_id: . C. Select prod_id, release_date, SUM(cost) FROM products GROUP BY prod_id. D. SELECT prod_id, release_date, SUM(cost) FROM products GROUP BY prod_id, release_date 显示答案