How many countries currently use the euro as their currency

The correct options are as follows:
1. C.
Denmark does not use Euro as its currency. Denmark uses the krone as its currency after negotiating the right to opt out from using euro currency. Although some political power prefer euro and had suggested that Denmark start using euro again, but most of the citizens do not buy this idea.
2. A.
Having a common currency makes it convenient for people in euro zones to move from one country in the zone to the other without having issues about exchange rate. It made trade and exchange very easy and convenient. 
3. D.
Portugal has adopted euro as its currency. The euro bank notes and coins were introduced as the only acceptable legal tender in Portugal on January 1, 2002. Three years before this time, euro had existed in Portugal as official currency but it was been used together with the Portuguese escudo as legal tender.
4. A.
The coal industries and the steel industries in Germany were shut down after world war ll due to economic reasons. Germany has few domestic resources. The most important mineral resources that Germany has is crude oil, followed by bituminous coal.
5. B. 
Single market refers to an association of many countries which trade with one another without restriction or tariffs.  Eu economy is an example of this, there are no trade restrictions among the member countries. Also, there is no restriction to free movement of people from one country to another among the member countries.
6. A.
The steel and coal industries of Spain and Denmark did not help to restore Europe's prosperity after the world war ll. A lot of money was spent on the war by Europe during world war ll; after the war, most of the countries were in financial crisis.Both Spain and Denmark economies were badly harmed after the war. European recovery program was launch to help restore the financial status of Europe.
7. A.
The creation of a single European market will promote competition; competition will force the suppliers to reduce their prices in order to attract customers and this in turn will increases the power of the consumers. The consumers will have many sources to get their goods from and will not be forced to adhere to any supplier whose product is not satisfying them.
8. C.
Denmark uses krone as its currency and does not use euro. A danish family who is eating out at a restaurant in Italy will have to paid for services rendered to them in euro since Italy uses euro as its legal tender. This may be a bit inconvenient.
9. D.
The principal reason where the European member countries came together is to strengthened trade and promote economic growth of each member country. Their coming together is a kind of networking which is aimed at achieving better results together.
10. D.
After the war, the economies of the European countries were in crisis and thing were bad, because huge amount of money had been spent on the war. The European countries were looking for a way of recovering their financial prosperity, it was during this time that Winston Churchill suggested that the European countries should form a united states in order to enhance  rapid economic recovery.