Which device type is commonly vulnerable to network breaches if not secured properly?

The selection of "All of the Above" as the correct answer highlights the fact that a variety of device types can indeed be vulnerable to network breaches if not secured properly. Each of the mentioned devices—routers, thermostats, and computers—play different roles in a network but can serve as entry points for attackers when adequate security measures are not in place.

Routers are critical for directing traffic in a network but can be misconfigured or have default passwords that expose them to attacks, allowing unauthorized access to the entire network.

Thermostats, particularly smart models, connect to home or office networks to allow remote management. If these devices are not secured, they can be exploited, enabling attackers to gain access to the network.

Computers are the most traditional endpoint in networks and can harbor numerous vulnerabilities, including software flaws or poor user practices, which can be exploited.

By identifying that all of these devices can be susceptible, the answer emphasizes the importance of comprehensive security practices that span all device types in a system, underscoring the concept that each connected device can potentially serve as a vector for network breaches if not adequately protected.