You are at a trading card convention, and observe that for a certain card, a dealer is willing to buy the card for $100, and sell the card for $120. At the same convention, a different dealer quotes a BID-ASK spread of $125-$140 for the very same card. Which statement is false: a. There is an arbitrage opportunity at the convention.
b. The market for trading cards is an inefficient market.
c. If the dealers ran into each other, they would happily trade with each other.
d. If you had to pay a 2% tax when you bought the card, you could not make a profit from this situation after taking transactions costs into account.