What could be the cause if a device cannot be activated?

When a device cannot be activated, several factors could contribute to this issue, and option C accurately addresses one of the potential underlying causes. A defective motherboard can lead to various hardware malfunctions that may prevent the device from booting up properly or communicating with necessary components, including those required for activation. Furthermore, an outdated operating system may also hinder the activation process, as updates often include critical fixes and compatibility improvements necessary for connecting to services that handle device activation.

While the other options mention factors like app versions, SIM card issues, and storage space, they each represent different types of challenges. For instance, outdated app versions might prevent certain applications from functioning correctly but typically wouldn't entirely block device activation. Similarly, a faulty SIM card can impact connectivity but may not necessarily prevent initial activation depending on the setup. Insufficient storage space can also interfere with the download and installation of updates, but it is less likely to impact the core functionality needed for device activation itself compared to hardware or OS malfunctions.

Thus, the combination of a defective motherboard and an outdated operating system presents a more substantial risk factor in successfully activating a device, justifying the choice of option C as the highlight in this scenario.