Refer to the exhibit.

Which Virtual Router Redundancy Protocol (VRRP) statement is true
about the roles of the master virtual router and the backup virtual router?

A.
Router A is the master virtual router, and Router B is the backup virtual router. When
Router A fails, Router B will become the master virtual router. When Router A recovers,
Router B will maintain the role of master virtual router.

B.
Router B is the master virtual router, and Router A is the backup virtual router. When
Router B fails, Router A will become the master virtual router. When Router B recovers, it
will regain the master virtual router role.

C.
Router A is the master virtual router, and Router B is the backup virtual router. When
Router A fails, Router B will become the master virtual router. When Router A recovers, it
will regain the master virtual router role.

D.
Router B is the master virtual router, and Router A is the backup virtual router. When
Router B fails, Router A will become the master virtual router. When Router B recovers,
Router A will maintain the role of master virtual router.

Explanation:
An important aspect of the VRRP redundancy scheme is VRRP router priority. Priority
determines the role that each VRRP router plays and what happens if the master virtual
router fails.

If a VRRP router owns the IP address of the virtual router and the IP address of the physical
interface, this router functions as a master virtual router.
Priority also determines if a VRRP router functions as a backup virtual router and determines
the order of ascendancy to becoming a master virtual router if the master virtual router fails.
You can configure the priority of each backup virtual router with a value of 1 through 254,
using the vrrp priority command.
For example, if Router A, the master virtual router in a LAN topology, fails, an election
process takes place to determine if backup virtual Routers B or C should take over. If
Routers B and C are configured with the priorities of 101 and 100, respectively, Router B is
elected to become master virtual router because it has the higher priority. If Routers B and C
are both configured with the priority of 100, the backup virtual router with the higher IP
address is elected to become the master virtual router.
By default, a preemptive scheme is enabled whereby a higher-priority backup virtual router
that becomes available takes over for the backup virtual router that was elected to become
master virtual router. You can disable this preemptive scheme using the no vrrp preempt
command. If preemption is disabled, the backup virtual router that is elected to become
master virtual router remains the master until the original master virtual router recovers and
becomes master again.
Reference:
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.5/addr_serv/configuration/guide/ic35vrrp.html