问题如下：
What are the most popular investments for life insurance companies?
选项：
A.Equities
Treasury bonds
Commercial paper
Long-term corporate bonds
解释：
D. Life insurance companies tend to invest in long-term corporate bonds. This allows them to match assets and liabilities. Equities and commercial paper do not allow them to do this. They prefer long-term corporate bonds to long-term Treasury bonds because on an actuarial basis they get well compensated for taking credit risk.
这里的长期公司债应该是信用质量比较高的公司债吧
