单选题 The primordial fireball would have been a dense roiling stew of radiation and elementary particles condensing out of the ______ energy, annihilating each other, recondensing, then colliding and disappearing all over again.

【正确答案】 A
【答案解析】colossal巨大的，庞大的；audacious大胆的，鲁莽的；ambient周围的；autonomous自治的。