Which statement describes an OSPF area for which no-summaries is configured?

A.
The ABR does not generate any Summary (Type 3) LSAs towards the backbone.

B.
The ABR does not generate any Summary (Type 3) LSAs for other OSPF areas.

C.
The area does not summarize external routes generated within its area.

D.
The area does not accept or create summaries of any kind.

Explanation:
Type 3 – Summary LSA – an Area Border Router (ABR) takes information it has learned on one of its attached areas and it can summarize it (but not by default) before sending it out on other areas it is connected to. This summarization helps provide scalability by removing detailed topology information for other areas, because their routing information is summarized into just an address prefix and metric. The summarization process can also be configured to remove a lot of detailed address prefixes and replace them with a single summary prefix, also helping scalability. The link-state ID is the destination network number for type 3 LSAs

Type 3 LSAs will pass into and out of the area. Unlike a normal stub area, the ABR will not inject a default route into an NSSA unless explicitly configured to do so. As traffic cannot be routed to external destinations without a default route, you’ll probably want to include one by appending default-information-originate (thanks to Adam for pointing this out).

http://packetlife.net/blog/2008/jun/24/ospf-area-types/