When a meander from the gulf stream pinches off and isolates a body of water within the center of the north atlantic gyre, the body of water is called a: ?

 "cold-core ring" .

The answer is a. it makes more sense then the other answers listed there.

They contributed many things, but here are some examples:

1) democracy - democracy as a political system was first implemented in ancient athens
2) some advances in mathematics - such as the pythagoras' law
3) the script - the roman script was adopted from ancient greek.