Fill in the blanks to make the following statements correct.

a. Economists have designed____________ to better explain and predict the behaviour we observe in the world around us.

b. A variable, such as price or quantity, that is determined within a theory is known as a(n)________ variable. A variable that is determined outside the theory is known as a(n) _________ variable.

c. When, based on a theory, we claim that "If A occurs, then B will follow," we are making a__________ that can then be tested by_________ observation.

d. If we observe that when variable \(A\) decreases, variable \(\mathrm{B}\) also decreases, we can say that the two variables are ___________ We cannot necessarily say that there is a __________ relationship between \(\mathrm{A}\) and \(\mathrm{B}\).

e. An important assumption that is made in economics is that individuals and firms pursue their own __________  We assume that individuals seek maximize their __________ and firms seek to maximize their ______________.