Virulence factors are components or attributes of pathogens that enable them to cause disease. The options provided include:
A. Adhesins - These are molecules that help pathogens adhere to host tissues, contributing to their virulence.
B. Toxins - These are harmful substances produced by pathogens that can damage host tissues or disrupt normal physiological functions.
C. Host antibodies - These are part of the host's immune response and are not factors produced by the pathogen themselves.
D. Capsules - These are protective outer layers found on some pathogens that can help them evade the immune system, contributing to their virulence.
E. None - This option suggests none of the above selections are excluded from being virulence factors.
Based on the definition of virulence factors, the correct answer is:
C. host antibodies