If TD posts 1.01$/ - 1.02 $/ bid-ask exchange rates, Scotiabank posts 0.7 /$ 0.8 /$, and Barclays posts 0.67 / - 0.68 / exchange rates, then:

a) Arbitrage is not possible

b) If you start with dollars, the only way to make arbitrage is to exchange currencies in the following direction: $ to to to $.

c) If you start with dollars, the only way to make arbitrage is to exchange currencies in the following direction: $ to to to $.

d) If you start with dollars, you can make arbitrage by exchanging currencies in any of the following directions: $ to to to $ or $ to to to $.