It's libby's first day in college. when she approaches the professor to have an "add" form signed, she listens to other students to see if they address the professor as "professor," "dr.," "mrs.," or by her first name, and then she does the same. this is an example of

This is an example of imitation/copying.

Imitation is a way of behavior where an individual observes and replicates the behavior of others. It is a reproduction of an act that is simulated by the perception of a similar act by another animal or person.

To imitate/copy somebody or something a model is needed. The copying may be done none-consciously ( seeing and copying others without thinking about the reason to do it ,) or it can be a conscious strategy ( out of uncertainty how to act or behave in some situation).

In Libby's case, the act of imitation comes as a conscious process of wanting to behave correctly and to fit in with others.The other students are Libby's model to copy her behavior from.

marginal cost is a microeconomic measure that us to evaluate the extent to which the level of production of a good is sustainable in accounting, that is, to how many quantities the company plans to profit from the production of the good.

the concept of marginal cost is simple, it means the cost of producing one more item. for example, in the case of pies, the marginal cost is the cost of producing one more pie than those that have already been produced.

it is important to understand that productive activity influences marginal cost. the marginal cost of some goods can be very high, while others may be insignificant. for example, the marginal cost of producing an extra plane is very high. already the marginal cost of a water company to provide 1l more water is derisory.

in the case of pies, the cost involves the inputs, the labor and the fixed cost, which involves the fixed space of the bakery. the level of production initially has the marginal cost decreasing because there is space and manpower available. however, to produce more you have to hire more workers and buy more inputs. if physical space is limited, workers will conflict with places, inputs and their productivity will decrease, meaning there is an optimum point of production for each level of space and manpower. from this point on, the productivity of the workers will be getting smaller because of lack of space, so that the marginal cost of producing one more pie will be increasing. so, although you have not posted the chart, but if you have the answer, you can see that my explanation goes according to the marginal cost curve that will increase from the 4th pie, answer (c).

the answer to your question is,

old stone age.

-mabel < 3