Where should you avoid parking or leaving a vehicle idling on a highway outside an urban area, especially when you can park off the road?

• On the paved part of any highway outside of a business or residential district
  Explanation:

  "Never park or leave a vehicle to stand idling on the paved part of any highway outside of a business or residential district when you can park off the road."
• In a designated rest area
• On the unpaved part of the highway next to the shoulder of the road
• None of the above