Joe sold gold coins for $1,000 that he bought a year ago for $1,000. he says, "at least i didn't lose any money on my financial investment." his economist friend points out that in effect he did lose money because he could have received a 3 percent return on the $1,000 if he had bought a bank certificate of deposit instead of the coins. the economist's analysis in this case incorporates the idea of

The answer is Opportunity Cost.

Explanation:

Joe sold gold coins at the same price on which he bought them. In his opinion, he is at a break even point with no profit no loss situation. But his economist friend told him that he is at a loss because he could have earned 3% return on his investment if he had bought the bank certificates of deposits.  So this Joe missed an opportunity of earning 3% return on investment. So we can assume that Joe hold the gold coins at an opportunity cost of 3% return on investment.

the assumption the narrator makes in this excerpt is that the messages he heards were going to hurt the narrator's mom; the narrator just springs in to action. the narrator doesn't specify in this excerpt why he believes that the messages present a problem that requires protection.