Consider your decision to read this textbook on economics. Identify which of the four core principles of economics is most relevant for the following aspects of that decision. 

a. Reading this textbook will help establish a solid foundation for understanding concepts you will learn in more advanced economics courses. 

b. Reading this textbook will require time and effort, but doing so will help you improve your grade in this course. 

c. The time you will spend reading this textbook could instead be used to study for your chemistry exam.

d. Each extra page that you read and each practice problem that you complete will help you increase your understanding of the material.