A planned EBGP network will use OSPF to reach the EBGP peer addresses. Which of these conditions should be avoided in the design that could otherwise cause the peers to flap continuously?

Blocking TCP 179 in one direction prevents the BGP session from ever forming at all, not causing a flap cycle once established.

When the peer IP address is advertised via EBGP, the router may resolve the next-hop to that peer through a BGP-learned route rather than the intended OSPF route. If the BGP session drops, the BGP route is withdrawn, making the peer unreachable, which prevents re-establishment - creating a self-referential loop that causes continuous flapping.

Using a non-backbone OSPF area for peer reachability is a design consideration but does not inherently create a recursive routing dependency or continuous flapping.

Reaching an EBGP peer via an OSPF-advertised default route is stable as long as the default route persists; it does not create a recursive dependency between BGP session state and route reachability.