In event of global warming, which one of following is most likely to occur?

It is believed that increase in concentration of greenhouse gases has resulted in rise of atmospheric temperature which is slight in tropics, moderate in middle latitudes and maximum in polar regions. Global warming could raise sea level due to thermal expansion of sea water, melting of glaciers and Greenland ice sheet. There is a danger of submersion of large area as one third of human population lives within 60 km of coastline. Coastal salt marshes and estuaries, wetlands, drylands, freshwater supplies, fisheries, fish breeding areas and other types of wildlife will undergo extinction.

So, the correct answer is 'The anticipated rise in sea level will be caused primarily by the melting of polar ice caps'.