问题如下：
An agricultural firm operating in a perfectly competitive market supplies wheat to manufacturers of consumer food products and animal feeds. If the firm were able to expand its production and unit sales by 10% the most likely result would be:
选项：
A.a 10% increase in total revenue.
B.a 10% increase in average revenue.
C.an increase in total revenue of less than 10%.
解释：
A is correct.
In a perfectly competitive market, an increase in supply by a single firm will not affect price. Therefore, an increase in units sold by the firm will be matched proportionately by an increase in revenue.
考点：完全竞争市场下厂商的总收入
解析：在完全竞争的市场条件下，P=MR
虽然题目中的厂商把单位售价提高10%，但是农场品市场是完全竞争市场，厂家只是价格的被动接受者。最后该厂商只能以原来价格卖出产品。但是产量增加了10%,所以总收入增加了10%。B,C选项说法都不对。
b为什么不对？
