问题如下：
An analyst notes that the fixed-income portfolio manager has strong views about the effects of macroeconomic factors on credit markets and follows a top-down investment process. According to this, the most appropriate risk attribution approach for the fixed-income manager is to
选项：
A.decompose historical returns into a top-down factor framework.
B.evaluate the marginal contribution to total risk for each position.
C.attribute tracking risk to relative allocation and selection decisions.
解释：
C is correct.
The portfolio is managed against a benchmark, which indicates a relative-risk type of risk attribution analysis. For a top-down investment approach, the analysis should attribute tracking risk to allocation and selection decisions relative to the benchmark.
B为什么不对，不也是top down+absolute的一种方法么
