In the article you read, the number of cases of paralytic polio went from about 2,500 per year in the 1950s to complete eradication in the americas by 1994. explain how the use of cell technology makes disease eradication possible.

Oral polio vaccine is highly effective and inexpensive (about US$0.10 per dose, or US$0.30 per child and its availability has bolstered efforts to eradicate polio. A study carried out in an isolated Eskimo village showed that antibodies produced from subclinical wild virus infection persisted for at least 40 years. Because the immune response to oral polio vaccine is very similar to natural polio infection, it is expected that oral polio vaccination provides similar lifelong immunity to the virus.

Contact immunity to polio can occur when attenuated poliovirus derived from the oral polio vaccine is excreted, and infects and indirectly vaccinates unvaccinated individuals.

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation: