从产品表Products中查询前10行商品的单价UnitPrice之和,正确的SQL是()
A. SELECT TOP 10 SUM(UnitPrice) AS单价之和FROM Products
B. SELECT SUM(UnitPrice) AS单价之和TOP 10 FROM Products
C. SELECT TOP 10 COUNT(UnitPrice) AS单价之和FROM Products
D. SELECT SUM(UnitPrice) TOP 10 AS单价之和FROM Products