题目：
Circuit-switching technology is used in Public Switched Telephone Network (PSTN), Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). It is a（）information transfer mode.
A.connection oriented
B.connectionless
C.high bandwidth utilization
D.poor real-time
答案：
参考答案：A
解析：电路交换技术用户PSTN、GSM和CDMA，它采用的是面向连接的通信方式。所以A正确。
