What Do We Mean by the Big Bang

What do we mean by the Big Bang?

A) the cosmic explosion at the beginning of the universe and the origin of the cosmic expansion that we now observe
B) the projected end of the universe, the result of the cosmic collapse that will inevitably follow the cosmic expansion we now observe
C) the cataclysmic event that produced our solar system about 13.7 billion years ago
D) the tremendous explosion that occurs when a quasar becomes a black hole, sending gravitational waves and cosmic rays throughout the universe