Answer:
increasing returns to scale
Step-by-step explanation:
The biggest barrier for other firms are increasing returns to scale. This is because Eric and Chris have their company already established and also have their clientele all hooked up and using their service. This allows them to produce a much higher electrical output for their clients with a certain Income. Newer companies will need a much higher income just to be able to produce a similar electrical output in order to try and compete with Eric and Chris.