I'm assuming you mean topographic maps, in that case C. Elevation
Most of the coast along the Mediterranean Sea is very dry.
The reason why the answer is the Mediterranean is because the climate is usually super dry and rarely has any rain.
What does the question say?
The main sources are humans which is why it is stated that the global warming is man made. The levels have increased beyond all measure, increasing since the 1950s by a 100 CO2 parts per million, and it keeps increasing by 2ppm on a yearly basis. The statistics from the industrial revolution era are not much different and show how much we've increased the CO2 in modern times.
