Under what circumstances will a routing loop occur between RTA and RTB?

In the network shown in the figure, the static route ip route-static 0.0.0.0 0.0.0.0 s1/0 is configured on RTA, and the static route ip route-static 10.0.0.0 23 s1/0 is configured on RTB.

Under what circumstances will a routing loop occur between RTA and RTB? (Multiple choice)
A . If the network connection between PCA and RTA is broken, a loop will occur between RTA and RTB.
B. If the network connection between PCB and RTA is disconnected, there will be a loop between RTA and RTB.
C. If the network connection between PCC and RTA is disconnected, a loop will occur between RTA and RTB.
D. If the network connection between PCD and RTB is disconnected, a loop will occur between RTA and RTB.

Answer: AB