Is it allowed for people to ride on the outside of your vehicle like in a pick-up truck if there is no space inside?

• Yes, it is allowed.
• Yes, it is allowed and preferred.
• No, it is not allowed if there is traffic.
• No, it is not allowed at all.
  Explanation:

  "When you are driving, you must not allow anyone to ride on the outside of your vehicle. This includes the open box of a pick-up truck. You and the other person can be charged for this offence."