Megan has been feeling stressed about being pregnant and has been having a glass of wine and a cigarette to help calm down. However, her unborn baby seems to get agitated and move around after Megan drinks and smokes, so she drinks and smokes more. These reoccurring events may alter the child's molecular pathways in ways leading to health and behavior challenges later in this child's life as well as in this child's future offspring. This illustrates the concept of:

A. teratogen cycling

B. embryonic differentiation

C. fetal programming

D. reciprocal proliferation