Answer:
The correct answer is option - a surface protein allowing the pathogen to bind to host cells
Explanation:
Virulence factors are substances or molecules released by pathogens such as bacteria, fungi, viruses and protozoa that enhance their function effectiveness and enable them to get the following-
Attachment to host cell and surface.
Evasion of the immune response of the host.
Suppression or inhibition of the immune response of host.
Getting nutrition from the host cells
Thus, the correct answer is option - a surface protein allowing the pathogen to bind to host cells.