请问老师B为什么错了，谢谢！

问题如下：

A bond market in which a communications network matches buy and sell orders initiated from various locations is best described as an:

选项：

organized exchange.

open market operation.

over-the-counter market.

解释：

C is correct.

In over-the-counter (OTC) markets, buy and sell orders are initiated from various locations and then matched through a communications network. Most bonds are traded in OTC markets. A is incorrect because on organized exchanges, buy and sell orders may come from anywhere, but the transactions must take place at the exchange according to the rules imposed by the exchange. B is incorrect because open market operations refer to central bank activities in secondary bond markets. Central banks buy and sell bonds, usually sovereign bonds issued by the national government, as a means to implement monetary policy.

考点：OTC

解析：OTC市场，来自不同地方的买卖订单通过network即可进行配对交易，故选项C正确。