In B, the structure of noted... that the elephant, giving rides ..., had been earning falsely implies that the reader already knows about the elephant--that is, that the existence of this particular elephant is not new information.
还有og的解释:Choice C may be faulted for distortion of meaning and diminished clarity because it suggests that the point of Wootton's example was the elephant's very existence; comparative earnings are presented (after and) as incidental detail 什么意思吖?