The correct answer is - C.) eliminating barriers to trade benefits the economies of member nations.
The regional trade blocs, in fact all trade blocks, are very useful for the economies of the countries that are members in the trade block. The benefit can be seen in the economic sector, as the countries can both, export products on larger markets without tariffs, and import products without imposing tariffs, which benefits the consumers as the prices are lower in that way.
The trade blocks have become a common thing in the world during the 20th century, and that has helped the economies of lot of countries, as well as the choices available and buying power of the consumers.
1. Tectonic
2. Subtropical
3. Aborigine
4. Desalination
The moisture is the same throughout the air mass.
The trolleys have been reduced over the last decades, after their initial increase as a public transportation, when new and better ways were discovered/produced for transport, their decline has started.
The buses since their invention, had grown in number and became a very important part of every city's public transportation, and still are.
The rapid transit is the most recent one of the mentioned in here. It's popularity has grown, number increased, and is very practical because it is not causing traffic mess. It is very important transport asset nowadays and makes lives of millions of people much easier.