Which of the following device is used to connect two dissimilar networks ?

Hub
Bridge
Gateway
Repeater

The correct answer is (c) Gateway.

A gateway is a device that connects two dissimilar networks. It translates data from one network protocol to another so that the networks can communicate. For example, a gateway can connect a LAN (local area network) to the Internet.

A hub is a device that connects multiple devices on a single network. It does not translate data, so it cannot be used to connect two dissimilar networks.

A bridge is a device that connects two similar networks. It does not translate data, but it can filter traffic between the networks to improve performance.

A repeater is a device that amplifies a signal so that it can travel over a longer distance. It does not translate data or connect networks.