What reason justifies an unexpected pull from the roadway into the “hard shoulder”?

1. Correct answer: Sudden appearance of an undesirable element in the driving lane.
2. When another vehicle stops in the opposite lane without giving an appropriate signal.
3. Ringing of the vehicle's cellular phone.
4. Technical malfunction in the vehicle’s air conditioning system.

WhySwerving onto the shoulder unexpectedly is justified if something suddenly appears in your lane. A phone call or the air conditioning is no reason.