are unsecured obligations that are not tied to specific assets for collateral. a. Bearer bonds b. No-load stocks c. Penny stocks d. Junk bonds

The correct answer is letter "D": Junk bonds.

Explanation:

A junk bond is a debt security that is poorly rated because it has a high default risk. Junk bonds are also called high-yield or speculative bonds. These are considered riskier investments than higher-rated bonds and thus offer a higher interest rate per year.

Junk bonds can be issued by corporations or governments and have a principal amount, maturity date, and coupon but they are not linked to specific assets as collateral.