In which scenario is it allowable to use a cellphone while driving?

Using a cellphone while driving is regulated to ensure the safety of both the driver and others on the road. The correct choice is when using hands-free technology because it allows the driver to maintain control of the vehicle while using the phone. Hands-free devices enable drivers to make calls or interact with their devices using voice commands, which minimizes distractions and reduces the need to physically handle the phone.

In contrast, the other options present scenarios where cellphone use is either discouraged or not allowed. Being stopped at a traffic light does not classify as a safe opportunity to use a cellphone, as this can lead to distractions when the driver should be focused on the traffic ahead. Similarly, driving on a rural road offers fewer distractions than urban environments; however, it does not exempt a driver from the risks of using a cellphone. Lastly, being alone in the vehicle might reduce some potential distractions, but it does not change the legal limitations around cellphone use while driving. Thus, hands-free technology is the only scenario explicitly allowing cellphone use while still prioritizing safety.