An enterprise OSPF domain has an ABR connecting the backbone (area 0) to a stub-like area (area 20) that contains an ASBR redistributing static routes from a partner network. The design team wants area 20 to allow its locally originated external routes to be advertised into the rest of the OSPF domain, but block Type 5 LSAs from other ASBRs from entering area 20. Which area type must be configured on area 20 to meet both requirements?