Which Is NOT an Illustration in Support of the Argument

Which is NOT an illustration in support of the argument that the intelligence quotient (IQ) score partly reflects the quality of a child's environment?

A) The Flynn effect shows a worldwide rise in IQ scores over the course of a century.
B) After being ill and missing a good deal school,a child's IQ score may decline.
C) After undergoing life stress,a child's IQ scores may decline.
D) IQ scores normally change a good deal from year to year in a person's life.