Which of the following is true concerning environmental influence on genetic expression?
A) It is impossible to alter in any way the expression of a gene in humans.
B) The only time a gene can be influenced by environmental factors is in the second trimester of pregnancy.
C) Environmental factors determine the way in which 90 percent of our genes are expressed.
D) Drugs and nutrition can alter normal gene expression.
Answer: D) Drugs and nutrition can alter normal gene expression.