2. 依據Rule 8 (c) If there is sufficient sea-room, alteration of course alone may be the most effective action to avoid a close-quarters situation provided that it is made in good time, is substantial and does not result in another close-quarters situation.，以下何者符合close-quarters situation的定義？ (A) CPA接近於0就算 (B) 相對方位沒有明顯變化就算 (C) 雙方有碰撞危機存在就算 (D) 靠單方採取避讓行動，已無法解除碰撞危機就算