Which of the following is true about antigens?

Antigens are substances that provoke an immune response in the body, which are primarily associated with pathogens such as viruses, bacteria, and fungi. When these foreign substances are detected, the immune system activates, producing antibodies to neutralize or destroy the pathogens bearing the antigens. This is a critical part of the immune response, allowing the body to recognize and remember specific pathogens for future defense.

The other options do not accurately describe the role or nature of antigens. While some substances can improve health, they do not function in the capacity of an antigen. Vitamins serve a different, clearly defined role in metabolic processes and are not classified as antigens. Additionally, while hormones are crucial for various bodily functions, they do not directly interact with antigens in the role of regulating them. Thus, the assertion that antigens are produced by pathogens accurately captures their essence and function within the immune system.