问题如下：
The short-term breakeven point of production for a firm operating under perfect competition will most likely occur when:
选项：
A. price is equal to average total cost.
B. marginal revenue is equal to marginal cost.
C. marginal revenue is equal to average variable costs.
解释：
A is correct.
Under perfect competition, price equals marginal revenue. A firm breaks even when marginal revenue equals average total cost.
考点：盈亏平衡点
解析：盈亏平衡点下：边际收益=平均总成本。
在完全竞争的市场条件下，边际收益=商品价格
所以可得，价格=平均总成本
B选项是利润最大化的条件
C选项是打酱油的选项。
P=ATC 不是长期均衡点的时候吗？