What is the Pulse Polio Programme of the Government of India? What is $OPV$? Why is it that India is yet to eradicate Polio?

(N/A) The Pulse Polio Programme is an immunisation campaign established by the Government of India to eliminate poliomyelitis (polio) by vaccinating all children under the age of five years against the polio virus.
The project fights poliomyelitis through a large-scale pulse vaccination programme and active surveillance for polio cases.
In $1995$,following the Global Polio Eradication Initiative of the World Health Organization $(1988)$,India launched the Pulse Polio Immunisation Programme alongside the Universal Immunisation Programme,which aimed at $100\%$ coverage.
The last reported cases of wild polio in India were in West Bengal and Gujarat on $13$ January $2011$. On $27$ March $2014$,the World Health Organization $(WHO)$ declared India a polio-free country,as no cases of wild polio had been reported for three years.
$OPV$ stands for Oral Polio Vaccine. It uses a weakened (attenuated) poliovirus and is administered orally.
Regarding the eradication status: India was officially declared polio-free by the $WHO$ in $2014$. While wild poliovirus has been eradicated,the country maintains strict surveillance to prevent the re-importation of the virus and to manage vaccine-derived poliovirus cases.