Consider the network shown below.

Suppose AS3 and AS2 are running OSPF for their intra-AS routing protocol. Suppose AS1 and AS4 are running RIP for their intra-AS routing protocol. Suppose eBGP and iBGP are used for the inter-AS routing protocol. Initially suppose there is no physical link between AS2 and AS4. Router 4b learns about prefix x from which routing protocol: OSPF, RIP, eBGP, or iBGP?

RIP

OSPF

eBGP

iBGP