单项选择题
According to the passage, which of the following is NOT a factor in the complete understanding of price（）
A．Instructions that come with a product. B．The quantity of a product. C．The quality of a product. D．Guarantees that cover a product.
单项选择题 What is the best title for the passage（）
单项选择题 According to the passage, the price system is related primarily to （）
单项选择题 The paragraph following the passage most likely discusses （）
