Economics is defined by
a. the study of scarcity in situations of rational choice.
b. the study of rational choice in situations of scarcity.
c. the study of supply and demand.
d. none of the above

Rick is a toddler with an easy temperament and active nature. people are often seen stopping to talk to him in supermarkets and parks where his mother takes him in the evenings because he smiles willingly at other children and adults. this aspect of rick’s behavior most likely reflects a(n) active genotype–environment interaction suppressive genotype-environment interaction passive genotype–environment interaction evocative genotype–environment interaction