When multiple users are editing the configuration on a Junos device, what is the default behavior when a user issues a commit command?

When multiple users are editing the configuration on a Junos device, what is the default behavior when a user issues a commit command?

A. The user's configuration changes are committed, other users configuration changes are still pending B. The user's configuration changes are committed, other users will be exited from the configuration mode C. All valid configuration changes made by all users will take effect D. The user will receive an error message disallowing a commit of the configuration