When is it permissible to use a mobile phone while driving?

Using a mobile phone while driving is primarily about safety and minimizing distractions. The correct answer recognizes that hands-free technology allows drivers to maintain better control of their vehicle compared to holding the phone to their ear. This technology can help reduce the cognitive load and visual distraction that comes with using a phone directly.

Additionally, using a mobile phone in emergencies is necessary for safety; it allows drivers to call for help or report dangerous situations without further endangering themselves or others. This practice aligns with many traffic laws and regulations that encourage responsible use of mobile devices while ensuring that drivers can respond quickly to emergencies.

The other options suggest scenarios that could lead to increased risks. For example, using a mobile phone when traffic is light could still divert attention away from the road, creating potential hazards. The idea that a phone can be used "whenever necessary" is too vague and could promote unsafe behaviors. Finally, while it's safest to use a phone only when parked, the reality is that emergencies can arise, necessitating hands-free communication. Thus, the guidelines related to the correct answer prioritize safety while allowing for critical communication needs.