Refer to the exhibit. An engineer configured R2 and R5 as route reflectors and noticed that not all routes are sent to R1 to advertise to the eBGP peers. Which iBGP routers must be configured as route reflectors to advertise all routes to restore reachability across all networks? 

Answer options:

A. R1 and R4
B. R1 and R5
C. R4 and R5
D. R2 and R5

C