Based on the show ip route isis output on R1, which statement is true? （）
- A The i su 10.1.0.0/23 route is a suppressed route.
- B The i su 10.1. 0.0/23 route is a summary route.
- C The i su 10.1.0.0/23 route is an IS - IS external route.
- D The R1 IS - IS router is an ASBR.
- E The R1 IS - IS router is an ABR that belongs to multiple IS - IS areas.
- F The R1 IS - IS router is performing route aggregation and is suppressing the more specific 10.1.0.0/23 prefix.