Question

debt investment
many investors invest in debt by purchasing securities, which can be bought and sold.
consumers and businesses are able to purchase bonds from governments and private companies, which are debt certificates.
investors can also purchase by buying the rights to loans and mortgages.
debts
equity

Explanation:

The text is about debt investment. Investors can invest in debt by purchasing securities like bonds. Buying the rights to loans and mortgages is also a form of debt - related investment, so the appropriate choice is debts as it relates to the overall theme of debt investment. Equity is a different type of investment not related to the context here.

Answer:

debts