Final answer:
The protective mechanisms against bacteria include phagocytosis, production of fever, and activation of complement. 'Alteration of surface antigens' is not a protective mechanism but a strategy used by bacteria to evade the immune system, making it the correct answer to the question.
Step-by-step explanation:
All of the following are protective mechanisms against bacteria EXCEPT:
In response to the student's question, each option listed apart from 'Alteration of surface antigens' is a known protective mechanism that the human body employs against bacterial pathogens.
Phagocytosis is a process in which phagocytes, such as macrophages and neutrophils, engulf and digest pathogens. Production of fever is a response to infection that can create an environment less conducive to bacterial growth. Activation of complement is a part of the immune response where antibodies attached to the surface of a pathogen activate the complement system. This can lead to the direct destruction of pathogens or assist other components of the immune system in identifying and eliminating them.
"Alteration of surface antigens," on the other hand, refers to a strategy that certain pathogens use to evade a host's immune response by frequently changing their surface proteins. Therefore, it is the correct answer to the question as it does not serve as a protective mechanism utilized by the body, but rather a mechanism used by bacteria to avoid being targeted by the host's immune defenses.