Which of the following LAs are transmitted only within a single area?

A, B, C and D.

OSPF uses a LSDB (link state database) and fills this with LSAs (link state advertisement). Instead of using 1 LSA packet OSPF has many different types of LSAs and in this lesson I’m going to show all of them to you.
   LSA Type 1:            Router LSA
   LSA Type 2:            Network LSA
   LSA Type 3:            Summary LSA
   LSA Type 4:            Summary ASBR LSA
   LSA Type 5:            Autonomous system external LSA
   LSA Type 6:            Multicast OSPF LSA
   LSA Type 7:            Not-so-stubby area LSA
   LSA Type 8:            External attribute LSA for BGP

Hi simon.waweru,
The answer is AD.

Router-LSAs (Type 1) are generated by each device and describe the link status and cost of the device. Router-LSAs are advertised in the area to which the device belongs.

Network-LSA (Type 2): generated by a designated router (DR) to describe the link status of the local network segment and advertised in the area to which the DR belongs.

Network-summary-LSA (Type 3): ABR generates a route to a network segment in an area and advertises the route to the non-totally stub or NSSA area that advertises or receives the LSA.

ASBR-summary-LSA (Type 4): An ABR generates a route to an ASBR and advertises the route to other areas except the area where the ASBR resides.

AS-external-LSA (Type 5): It is generated by an ASBR to describe routes to the outside of an AS and advertised to all areas except stub areas and NSSAs.