问题如下：
The discussion turns to benchmark selection. DFC’s previous fixed-income manager used a custom benchmark with the following characteristics:
Characteristic 1：The benchmark portfolio invests only in investment-grade bonds of US corporations with a minimum issuance size of $250 million.
Characteristic 2：Valuation occurs on a weekly basis, because many of the bonds in the index are valued weekly.
Characteristic 3：Historical prices and portfolio turnover are available for review.
Which of the custom benchmark’s characteristics violates the requirements for an appropriate benchmark portfolio?
选项：
A.Characteristic 1
Characteristic 2
Characteristic 3
解释：
B is correct.
The use of an index as a widely accepted benchmark requires clear, transparent rules for security inclusion and weighting, investability, daily valuation, availability of past returns, and turnover. Because the custom benchmark is valued weekly rather than daily, this characteristic would be inconsistent with an appropriate benchmark.
为什么不选A？
另外，有哪些custom benchmark’s characteristics follow the requirements for an appropriate benchmark portfolio?
