However, at times this balance in nature is ________, resulting in a number of possibly unforeseen effects.
句意：然而，有时这种平衡会受到干扰，从而导致一些可能无法预料的后果。disturb弄乱；打扰。trouble麻烦；confuse使烦恼。 使困惑；混淆。puzzle使……困惑；使……为难。由此可推断正确答案为B。