Refer to the PE1 router routing table output exhibit.

What is causing the i su 10.1.10.0/24 [115/30] via 0.0.0.0, 00:40:34, Null0 entry on the PE1 router
routing table?

A.
The PE1 router is receiving the 10.1.10.0/24 summary route from the upstream L1/L2 IS-IS
router.

B.
The PE1 router has been configured to summarize the 10.1.10.x/32 IS-IS routes to
10.1.10.0/24.

C.
The 10.1.10.0/24 has been suppressed because IS-IS auto-summary has been disabled on the
PE1 router.

D.
The 10.1.10.0/24 has been suppressed because of a route policy configuration on the PE1 router.

E.
The 10.1.10.0/24 has been suppressed because the more specific 10.1.10.x/32 IS-IS routes
have been configured to leak into the IS-IS non-backbone area.

Explanation: