I think that the best answer is that
C. The European Union has the largest economy in the world.
Coastal location encourages trade and fishing and temperate climate makes farming easier- those factors contribute to the economy, so they would make the economy of the EU quite strong!
A. You answer is the Arabian Sea.
In Earth's climate system, positive feedback's tend to amplify changes in the system, and negative feedback's tend to encourage the system against change. Having a positive feedback gives the newest updates and brings the problems on the table, thus changes are always a must when there's proof that suggest there's big problem, but when the feedback is negative, lacking, then there's not pressure for changes, so anyone who has interest in not changing will push for that, thus encouragement of taking no changes. <span />