The correct answer to the question is option 4, Pakistan. India has made a Polio Vaccination Certificate mandatory for Indian Visa applicants from Pakistan. This means that individuals from Pakistan who are applying for an Indian visa are required to provide a certificate that proves they have been vaccinated against polio.

It is important to note that this requirement is specific to applicants from Pakistan only and does not apply to individuals from other countries such as Bangladesh, China, or Indonesia.

The decision to make the polio vaccination certificate mandatory for Pakistani visa applicants is likely due to the fact that polio has been a public health concern in Pakistan. The country has had difficulties in eradicating the disease and has seen cases of polio transmission. By implementing this requirement, India aims to prevent the spread of the disease within its borders and protect the health of its citizens.

It is crucial for Pakistani visa applicants to ensure they have obtained the necessary polio vaccination and have the corresponding certificate before applying for an Indian visa. This requirement demonstrates the importance of public health measures in international travel and the efforts taken by countries to safeguard their population from diseases.