Final answer:
Proteins are the most antigenic class of molecules due to their complex three-dimensional structure, which enables them to effectively stimulate the immune response, both humoral and cellular.
Step-by-step explanation:
The class of molecules that is the most antigenic is proteins. Proteins have a complex three-dimensional structure which allows them to be highly effective and potent antigens, capable of stimulating both humoral and cellular immune responses. On the other hand, carbohydrates, lipids, and nucleic acids are less complex and therefore less effective as antigens. Carbohydrates can only stimulate humoral immunity while lipids and nucleic acids are generally the least antigenic, often requiring combination with proteins or carbohydrates to become antigenic.
Proteins are highly effective and potent antigens due to their three-dimensional complex structure, which allows them to stimulate both humoral and cellular immunity. Carbohydrates are less complex and can only stimulate humoral immune defenses. Lipids and nucleic acids are the least antigenic molecules unless they are combined with proteins or carbohydrates.