There are three interfaces on R5 which are Loopback0: 10.5.5.5 ; Loopback1: 10.5.5.55; Ethernet0/0: 192.168.123.5 and all of them are advertised via 192.168.12.2 so we can conclude traffic from R1 to R5 goes through R2 (192.168.12.2 is the IP address of S2/1 interface of R2).
Note: Maybe there is another version of this question in the exam in which the answer should be “The traffic is equally load-balanced over R2 and R3″. Therefore please check the “show ip route” output carefully to see if there are more than one route to the destination.