Final answer:
The poliovirus is primarily transmitted through the fecal-oral route, particularly through contaminated food and water, which is the correct answer to the question (option 3).
Step-by-step explanation:
The main route of transmission of the poliovirus is fecal-oral route. The virus enters the body through the mouth and initially replicates in the pharynx and gastrointestinal tract. Even without symptoms, infected individuals can shed the virus in their feces and oral secretions, thereby potentially transmitting it to others. Further replication can occur in the central nervous system if the virus enters the bloodstream, which could lead to paralysis and sometimes death. The fecal-oral route includes transmission through contaminated food and water. Therefore, the correct answer to the question regarding the main route of poliovirus transmission is food and water (option 3).