Why might you want to synchronize IGP and BGP convergence by advertising an infinite metric in OSPF or setting the overload bit in IS-IS? 

Answer options:

A. to prevent traffic loss when the path from a router to a BGP next hop traverses another router that has not yet learned the path via BGP
B. to prevent BGP from converging faster than IGP, which can cause temporary routing loops in the network
C. to prevent routes which are learned both from IGP and BGP from forming a routing loop
D. to prevent churning between multiple available routes reachable through IGP and BGP

A