All of the following are dangerous to do while driving. Which is also illegal?
- Wearing a headset that covers both ears. ✓
- Having one or more interior lights on.
- Using cruise control on residential streets.
Answer: A. Wearing a headset that covers both ears.
Of those three behaviors, the one that is illegal is wearing a headset that covers both ears.
Why this is the answer
The California Driver Handbook, in its section on health and driving, says hearing matters because you need to hear horns, sirens, motorcycles, and screeching tires that warn you of hazards. Right after that, it states flatly that wearing a headset or earplugs in both ears while driving is illegal. So covering both ears with a headset is not just risky in the handbook's view — it is against the law, which is what the question asks you to pick out.
Why the other answers are wrong
- B. Having one or more interior lights on. — Having interior lights on is a distraction you should avoid, but the handbook passage quoted here does not list it as illegal, so it does not fit the question.
- C. Using cruise control on residential streets. — Using cruise control on residential streets is unwise because traffic there keeps changing, but the handbook passage quoted here does not make it illegal.
Remember it
Think of your ears as safety equipment: the law lets you block one ear, but blocking both cuts off the horns and sirens you need.