When is it illegal to use a handheld wireless telephone while driving a motor vehicle in California?

Answer: D — Any time

It is always illegal to use a handheld wireless telephone while driving a motor vehicle in California, regardless of the circumstances. Option A may seem like a likely answer, as using a phone while stopped in traffic may seem harmless, but it is still considered distracted driving and therefore illegal. Option B may also seem plausible, as one may assume that emergency situations would allow for phone usage, but it is still against the law to use a handheld device while driving. Option C may be misleading, as driving in a school zone may seem like a specifically designated time when phone usage would be prohibited, but again, it is considered illegal at all times. This is because the use of a handheld device while driving is considered a dangerous and distracting behavior that puts both the driver and others on the road at risk. It is important to always follow the law and avoid using a handheld device while driving.