没读懂题

NO.PZ201909300100000301问题如下1 Of the three attribution approaches referenceTolmach, the methorequestethe committee:A.is the least accurate.B.uses the unrlying holngs of the actuportfolio.C.is the most fficult antime consuming to implement.A is correct. The committee scribea return-baseattribution, whiis the least accurate of the three approaches (the return-base holngs-base transaction-baseapproaches). Return-baseattribution uses only the totportfolio returns over a perioto intify the components of the investment process thhave generatethe returns.第二个描述的中文翻译？

这一题为什么不是holng base 或是transaction base呢？

这一题committe要求 (1) apply the attribution methothuses only eafuns totportfolio returns over the last 12 months to intify return-generating components of the investment process an(2) inclu the impaof specific active investment cisions anthe attribution effects of allocation ansecurity selection in the report。第一点看出来是return-base第二点specific active investment cisions不是指transaction-baseattribution吗？这个点在哪里呢，回去看讲义也没有找到

uses the unrlying holngs of the actuportfolio. is the most fficult antime consuming to implement. A is correct. The committee scribea return-baseattribution, whiis the least accurate of the three approaches (the return-base holngs-base transaction-baseapproaches). Return-baseattribution uses only the totportfolio returns over a perioto intify the components of the investment process thhave generatethe returns. 请问factor-base怎么反映security selection的，谢谢！