请问d选项为什么错了

问题如下：

Regarding correlation risk and credit risk, which of the following statements is correct?

选项：

A.

Generally, the long-term default probability of investment grade bonds is lower than short-term.

B.

The change in position concentration is directly related to the change in the default correlation.

C.

Bond investors are more willing to concentrate their positions in an industry, as this will allow for more in-depth research on this industry.

D.

For non-investment grade bonds, the probability of default is higher in the long run.

解释：

B is correct.

考点：correlation risk& credit risk

解析：

A：投资级债长期违约率会更高，因为没有万年老店

B：仓位的集中度会直接影响相关性风险

C：债券投资者会做行业分散，因为集中在一个行业的话相关性太高

D：垃圾债熬过短期困难的话，长期的违约率会降下来。