In response to an outbreak of swine flu in 1976, the United States government encouraged all citizens to receive a vaccination against the flu. Unfortunately, in some cases, vaccination led to paralysis and, in some cases, death. What is the most likely reason some people reacted badly to the vaccine?
a
The government did not inform the public about the health risks of the vaccine.
b
All of the vaccines produced were ineffective.
c
Many people were vaccinated quickly without assessing their general health.
d
The vaccines were all produced in the same factories.