A Major Factor in the Re- Emergence of Vaccine- Preventable

A major factor in the re- emergence of vaccine- preventable diseases in the early 21st century has been

A) microbes can develop resistance to vaccines just as they to do antibiotics.
B) a flawed research study incorrectly linking vaccination to autism was published in the late 1990s.
C) a flawed research study incorrectly linking vaccination to breast cancer was published in the late 1990s.
D) concerns about animal rights have led people to avoid pharmaceuticals and other products that might have been tested on animals.
E) fears of biological weapons after the September 11, 2001 terrorist attacks turned public sentiment against vaccines.