The World Health Organization (WHO) set a target to eradicate polio, using vaccination, by the year 2000. However, cases are still being reported in some parts of the world after this date.
What explains these new cases of polio?
1) Some parts of countries are difficult to reach because of poor transport or wars.
2) There is not enough research to develop more effective vaccines.
3) Records of vaccinated and unvaccinated people are incomplete.
1 )
1 only
2 )
1 and 2 only
1 and 3 only
4 )
2 and 3 only
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