Your question is OSPF vs BGP in Large-Scale Environments. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Describe the differences between routing protocols like OSPF and BGP in a large-scale environment.
Address their routing domains, path-selection mechanisms, convergence behavior, scalability, policy control, and typical placement in an enterprise or service-provider network. Explain how you would decide between OSPF, BGP, or using both together.