Say that someone brings several water samples to your laboratory.

that samples A and B are from the Atlantic Ocean and that one came from near the equator and the other from hear the Tropic of Cancer. But he does not know which one is which. He has a similar problem with samples C and D one is from the Red sea and the other is from the Baltic Sea. Applying your knowledge of ocean salinity, how would you identify the location of each sample? How were you able to figure this out?