Refer to the exhibit. OSPF is the PE-CE protocol. A backdoor link exists between the C-59 and C-62. Which two OSPF features are used to enforce that the backdoor link is used only for backup purpose? (Choose two.)
A. Increase the OSPF link cost between C-59 and C-62.
B. Configure a sham link between PE8 and PE9.
C. Apply site-of-origin feature on PE8 and PE9.
D. Configure a virtual link between C-59 and C-62.
E. PE8 must not import what PE9 is exporting and vice-versa.
