Duration funds have a certain duration. Take the stock as an example. As long as the company is there, the stock is there, and the bond itself has a set time.

B The main fund is a fund company, the stocks are enterprises, and the bonds are national, local governments and enterprises.

C Risk and income risk are bonds, funds and stocks increasing in turn, while income is stocks, funds and bonds decreasing in turn.

The equity management fund embodied in D is a trust relationship, which is equivalent to the agency investment of the fund company. Stocks are equity and bonds are creditor's rights.