Which of the following is not a mechanism employed by the human microbiota to contribute to the first line of defense? Multiple Choice
A. It can block potential binding sites on epithelial cells restricting adhesion, which is a necessary step for infection
B. It can out-compete pathogens for limited nutrients
C. It can lower the pH making the environment too acidic for pathogens to survive
D. It can phagocytose pathogens
E. It can train the immune cells to recognize antigenic markers
