Final answer:
Mutual funds, UITs, ETFs, and ETNs are adversely impacted if the issuer's credit rating is downgraded due to increased risk of default on the issuer's debt obligations.
Step-by-step explanation:
The products that are adversely impacted if the issuer's credit rating is downgraded are A. mutual funds, B. unit investment trusts (UITs), C. Exchange-traded funds (ETFs), and D. Exchange-traded notes (ETNs). When the issuer's credit rating is downgraded, it indicates that there is an increased risk of default on the issuer's debt obligations. As a result, the value of the products that rely on the issuer's creditworthiness may decrease, as investors perceive them to be riskier.