问题如下：
PZ’s financial statements adhere to generally accepted accounting principles, PZ overstate earnings when economy is recession and understate earnings when economy is booming，PZ’s financial statements are best categorized as:
选项：
A. GAAP, decision-useful, sustainable, and adequate returns
B. Within GAAP, but "earnings management"
C. GAAP, decision-useful, not sustainable, Low "earnings quality"
解释：
B is correct.
考点：Quality Spectrum Of Financial Reports
解析：这个题考的是一级财务的知识
题干说了公司是遵守会计准则的(GAAP)，注意这里不是指US GAAP，而是说公司遵守了普遍适用的会计准则，但是earning 有问题，所以选B。具体描述：Reporting is compliant with GAAP, but the amount of earnings is actively managed to increase, decrease, or smooth reported earnings.
B选项和C选项的区别在哪？请总结