Macroeconomics 20th Edition by Campbell McConnell,Stanley Brue,Sean Flynn

Exercise 24

Suppose that you are given a $100 budget at work that can be spent only on two items: staplers and pens. If staplers cost $10 each and pens cost $2.50 each, then the opportunity cost of purchasing one stapler is:
A) 10 pens.
B) 5 pens.
C) zero pens.
D) 4 pens