The correct answer is D. all of the above.
When a large current is interrupted, an arc is formed between the opened contacts. This arc can cause damage to the relay and the circuit it is protecting. To prevent this damage, arc suppressing blow out coils, wide separation of the opened contacts, and high speed opening of contacts are all necessary.
Arc suppressing blow out coils create a magnetic field that helps to extinguish the arc. Wide separation of the opened contacts increases the distance between the arcing contacts, which helps to break the arc. High speed opening of contacts reduces the amount of time that the arc is present, which also helps to extinguish the arc.
All of these methods are necessary to ensure the safe interruption of large currents.