问题如下：
If the time lag between when an order to trade a security is placed and when the order is executed increases, how does the market efficiency changes correspondingly?
选项：
A.Market efficiency decreases.
B.Market efficiency stays the same.
C.Market efficiency increases.
解释：
A is correct.
If the time lag between when an order to trade a security is placed and when the order is executed increases, it is an indication that operating inefficiencies increases and it reduces market efficiency.
这个题干怎么翻译，读不太懂。这个是交易延迟了，卡单了？还是一段时间内，被执行的订单数量增加了？
