OSPF vs. EIGRP Routing Protocol Transition

The responses provided in this post should help.

https://community.fortinet.com/t5/Support-Forum/Integrate-Fortigate-in-Cisco-Network-using-EIGRP/td-p/280172

Your description of the scope of the project is not so clear about the conditions surrounding the question. Are there any Fortinet products involved, like two sites have FGTs and using OSPF to route inside of the site, and one location has a Cisco router(s) (must be) to route internally at the site, and you're supposed to replace the Cisco router with FGT, and so on.

Or, it has nothing to do with any Fortinet products specifically, but just saying "sites" have "OSPF" and "EIGRP".  If that's the case, redistribution from EIGRP to OSPF and from OSPF to EIGRP at the EIGRP site is the answer. It would just "bridge" them. You should research this more in detail yourself instead of asking/cheating to get the answer from somebody else. I think that's your instructor's intention. 

Toshi