Monocytes, in conjunction with epithelium-derived factors, can act to facilitate which biological process?

The correct answer is - host immune system.

Explanation:

Monocytes are one of white blood cells or normally called leukocytes. Monocytes are the largest white blood cells and distinguished to the myeloid lineage dendritic cells and large monocytes known as the macrophages.  

Monocytes are the cells that influence the adaptive immunity in the particular host that is experiencing the infection of foreign particles or antigen. It is a part of all vertebrate innate immune system.

Thus, the correct answer is - host immune system.

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms

c. is the correct answer