Why does a router create an ASBRSum (Type 4) LSA?

Why does a router create an ASBRSum (Type 4) LSA?

A.
An ABR creates an ASBRSum (Type 4) LSA with the information contained in NSSA (Type 7)
LSAs it receives from NSSAs.

B.
An ABR creates an ASBRSum (Type 4) LSA to describe the router ID of ASBRs located in
other areas.

C.
An ASBR creates an ASBRSum (Type 4) LSA to describe its router ID so that routers in other
areas can reach the external networks it advertises.

D.
An ABR creates an ASBRSum (Type 4) LSA to summarize routes received from other areas.

Explanation: