Final answer:
Congeners and acetaldehyde in alcoholic beverages contribute to hangover symptoms, with acetaldehyde being particularly toxic. The correct answer is option C) and D).
Step-by-step explanation:
The substances in alcohol that may contribute to hangover symptoms are C) congeners and D) acetaldehydes. Congeners are impurities produced during fermentation that can add flavor to different alcoholic beverages. These include a variety of chemicals like acetone, acetaldehyde, tannins, and some flavoring agents in different drinks.
Acetaldehyde, in particular, contributes significantly to hangover symptoms. When ethanol is processed in the liver, the enzyme alcohol dehydrogenase converts it to acetaldehyde, which is significantly more toxic than ethanol itself. This acetaldehyde is then usually broken down into acetate by acetaldehyde dehydrogenase.
Methanol, which can be present in small amounts in alcoholic beverages, is also metabolized to formaldehyde and then to formic acid, both of which are toxic. It is the oxidation of methanol to methanal (formaldehyde) that is particularly dangerous, leading to tissue damage and potentially causing blindness.