A. <span>Exposure to an antigen
Exposure to viruses and antigens led to the foundation of modern vaccination. Vaccination introduces an antigenic material that helps the ability of the immune system to adapt a specific pathogen, therefore leading to a long-term immunity.</span>
Answer: Element
Explanation:
really just use ur deduction skills
The Algae. Unless you want to get into the microorganisms that contribute to the algae's growth.
Answer:
It would be mutualism because they both benefit from the situation
Explanation:
