问题如下：
In the latest guidelines for computing capital for incremental risk in the trading book, the incremental risk charge (IRC) addresses a number of perceived shortcomings in the 99%/10 day VAR framework. Which of the following statements about the IRC are correct?
I. For all IRC-covered positions, the IRC model must measure losses due to default and migration over a one-year horizon at a 99% confidence level.
II. A bank can incorporate into its IRC model any securitization positions that hedge underlying credit instruments held in the trading account.
III. A bank must calculate the IRC measure at least weekly, or more frequently as directed by its supervisor.
IV. The incremental risk capital charge is the maximum of (1) the average of the IRC measures over 12 weeks and (2) the most recent IRC measure.
选项：
A.I and II
B.III and IV
C.I，II，and III
D.II，III，and IV
解释：
B is correct. Statement I. is incorrect because the confidence level is 99.9%. Statement II. is incorrect because securitizations are subject to the banking book capital requirements. The other two statements are correct.
选项A和B分别错在哪里
.