The Supremacy Clause is a clause within Article VI of the U.S. Constitution which dictates that federal law is the "supreme law of the land." ... Under the doctrine of preemption, which is based on the Supremacy Clause, federal law preempts state law, even when the laws conflict.
Answer:
D. simple main effect of gender.
Explanation:
A simple main effect refers to the effect that one independent variable has at various different levels of a second independent variable. In this example, Reba is examining the interaction between age and gender. However, she mainly focuses on the effect of a single variable (gender) at various levels of a second variable (different ages). This type of research allows researchers to have a more complete view of the phenomenon at hand.
