A company has completed two acquisitions over the previous year. Each of the acquired companies was allowed to keep its own independent authentication server. The network administrator has been asked to roll out the Junos Pulse Access Control Service to users within the original company along with each of the two acquired organizations.The administrator configures three authentication realms, one for each independent authentication server, and associates them all with a single sign-in policy. All of the client endpoints are running Junos Pulse on their Windows XP desktops.
When a user signs in to the Junos Pulse Access Control Service, which statement is correct?（）

A. The first authentication realm that was added to the sign-in policy is used by default.
B. The user is allowed to choose the correct authentication realm from a list presented by Junos Pulse.
C. When Junos Pulse is initially installed on the desktop, it must be configured with the correct realm.
D. This is not an allowed configuration; the administrator should configure separate sign-in policies for each realm.