I don't believe the SG answer is correct for this task. I entered verbatim what the SG has and the 31.x.x.x routes from BB3 all show up.
RSRack26SW1#show ip route rip
132.26.0.0/16 is variably subnetted, 9 subnets, 2 masks
R 132.26.8.0/24 [120/1] via 204.12.26.8, 00:00:09, Vlan783
31.0.0.0/16 is subnetted, 4 subnets
R 31.3.0.0 [120/1] via 204.12.26.254, 00:00:13, Vlan783
R 31.2.0.0 [120/1] via 204.12.26.254, 00:00:13, Vlan783
R 31.1.0.0 [120/1] via 204.12.26.254, 00:00:13, Vlan783
R 31.0.0.0 [120/1] via 204.12.26.254, 00:00:13, Vlan783
150.26.0.0/16 is variably subnetted, 4 subnets, 2 masks
R 150.26.8.0/24 [120/1] via 204.12.26.8, 00:00:09, Vlan783
30.0.0.0/16 is subnetted, 2 subnets
R 30.3.0.0 [120/1] via 204.12.26.254, 00:00:14, Vlan783
R 30.1.0.0 [120/1] via 204.12.26.254, 00:00:14, Vlan783
CONFIG
--------
access-list 1 permit 30.0.0.0 0.254.255.255
!
router rip
version 2
offset-list 1 in 16 Vlan783
network 150.26.0.0
network 204.12.26.0
no auto-summary