John, a professional hacker, targeted CyberSol Inc., an MNC. He decided to discover the IoT devices connected in the target network that are using default credentials and are vulnerable to various hijacking attacks. For this purpose, he used an automated tool to scan the target network for specific types of IoT devices and detect whether they are using the default, factory-set credentials.
What is the tool employed by John in the above scenario?

A. IoT Inspector
B. AT&T IoT Platform
C. IoTSeeker
D. Azure IoT Central