The answer is logos. It is the appeal concerning
logical reason, therefore the speaker wants to present an argument that seems
to be comprehensive to the audience. It encompasses the content and point of
view of the speech. Like pathos and ethos the goal is to make a persuasive
outcome.
The economic term is the opportunity cost.
The concept of opportunity cost is a relatively inexpensive and relative measure that involves people's preferences, so it varies from person to person. It is a question of comparing what is left over when making a decision.
In Katie's case, the opportunity cost of the money she saves to buy a car is what she fails to do with that money. For example, she stops investing in stocks, fails to make a trip, etc.
All decisions involve an opportunity cost. Taking another example, the opportunity cost of studying for the test at the end of the week is measured by the loss of leisure you would have. However, the decision to study for the test is chosen because it is more valuable.
Because it protected the Egyptians, allowing them to create more inventions. I hope this helped you.
