Which of the following statements do you think indicate sound economic thinking? Explain your answer.

a. My parents paid for this economic course, Therefore, I’m going to attend every lecture even if it is useless and boring.

b. Because we own a house rather than rent, and the house is paid for, living in our own house does not cost us anything.

c. I own a desktop computer that I cannot afford to sell until I find a buyer who us willing to let me recover at least my original payment.