If a router has four interfaces and each interface is connected to four switches, how many broadcast domains are present on the router?

This would imply only one network segment, which contradicts the presence of four distinct interfaces.

This is incorrect as each interface forms its own broadcast domain, not just two.

Routers, by design, operate at Layer 3 and inherently segment broadcast domains; therefore, each of the four physical interfaces on the router defines a distinct broadcast domain. Any traffic originating from one interface's broadcast domain will not be forwarded as a broadcast to other interfaces unless explicitly routed.

This is an arbitrary number and does not reflect the one-to-one relationship between router interfaces and broadcast domains.