The correct answer is the Eurozone.
Members of the Eurozone use the EURO as their common currency.
Brexit refers to the referendum vote by the British people on the exit from the EU.
1) You choose which college to go to: each college you don't choose is an opportunity cost
2) you choose which language to learn. You can't learn them all. If you decide to learn Chinese, you might be missing out on Spanish
3)Where do you want to do your exchange? if You choose one place, you're missing out all the other opportunities.
