Final answer:
A bus topology has a single point of failure in its main network cable. If the cable encounters a problem, the entire network can become inoperative.
Step-by-step explanation:
In the context of network topologies, a bus topology is the network configuration that has a single main cable acting as the backbone for all the devices connected to the network. This single main cable would become a single point of failure because if it were to fail or become damaged, the whole network would likely stop functioning. This stands in contrast to topologies like a star topology, where each device is connected to a central hub, a full mesh topology, where every device is connected to every other device, and a partial mesh topology, which is similar to a full mesh but with some devices connected to all others and some only connected to a few. Only the bus topology has a single main cable that can cause the entire network to collapse if it encounters a problem.