请问为什么不能选C呢？C错在哪里？

问题如下：

To properly assess a company's past performance, an analyst requires:

选项：

A.high earnings quality. B.high financial reporting quality. C.both high earnings quality and high financial reporting quality.

解释：

Financial reporting quality pertains to the quality of the information contained in financial reports. If financial reporting quality is low, the information provided is not useful to assess the company’s performance. Financial reporting quality is distinguishable from earnings quality, which pertains to the earnings and cash generated by the company’s actual economic activities and the resulting financial condition.