According to the Centers for Disease Control (CDC),by the End

Multiple Choice

According to the Centers for Disease Control (CDC) ,by the end of September 2014,roughly 8,000 cases of whooping cough had been reported in California for that year; more than 250 patients (mostly infants and young children) were hospitalized with 58 of them requiring intensive care.Several other childhood diseases that were once common but then eradicated through high vaccination rates have returned since the antivaccination movement grew in the 1990s.The epidemiological data collected by the CDC indicates this resurgence of childhood diseases is most likely the result of

A) reduced herd/community immunity.
B) reduced vaccine effectiveness.
C) increased virulence of the pathogens causing these diseases.
D) simply the increased number of people present in the United States.