问题如下：
2 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.
请问从哪里看出来是相对的,我没有找到benchmark 另外，文中提到经理对于宏观因子有很强烈的观点，为什么不是factor base
