哪个是投treasury bond的？

问题如下：

What are the most popular investments for life insurance companies?

选项：

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.