Refer to the exhibit. An engineer must reduce the number of Type 1 and Type 2 LSAs that are advertised to R4 within OSPF area 0. Which configuration must be applied?

An NSSA (Not-So-Stubby Area) configuration on an Area Border Router (ABR) such as R1 for a specific area (even if 'area 0' is used contextually for a non-backbone NSSA area) is primarily designed to control the propagation of external routes. It converts Type 5 LSAs into Type 7 LSAs for internal area routing, preventing the flooding of external Type 5 LSAs, which helps reduce the LSA database size and improves convergence, although it does not directly reduce Type 1 or Type 2 LSAs within an area.

Configuring R4 as an NSSA area border router would not achieve the stated goal, and Area 0 itself cannot be configured as an NSSA area as it is the backbone.

Configuring a stub area on R2 would prevent Type 5 and Type 4 LSAs from entering that area, but it does not directly address the reduction of Type 1 and Type 2 LSAs within Area 0 and does not fit the NSSA context implied by the correct answer.

Configuring an NSSA Totally Stubby Area (no-summary) on R2 would prevent Type 3, 4, and 5 LSAs from entering that area; while reducing LSA types, it doesn't align with the specific choice A and Type 1/2 LSAs.