山西省煤矿井下作业人员管理系统中规定各煤矿入井井口必须安装（）。

A. NTP updates are sent in the timezone they are collected in，and the syslog server will adjust based on the input time.
B. NTP authentication verifies the source，not the recipient.
C. NTP authentication requires that the recipient has multiple strata clocks to ensure accuracy.
D. Secure NTP can be configured to use SHA-1 hashing，since NTP is very insecure.
E. A stratum 0 clock should be configured at the core of every network，so it can connect to an accuratetime source.