The correct answer is - B. Pieces of glaciers that fall into the sea.
The icebergs are small, medium, or very big pieces of ice that are floating in the oceans and seas in close proximity to the Arctic and Antarctic circles.
They form with the cracking of the glaciers, from which pieces of ice fall into the water, but because the water is very old, they do not melt, but continue their trip with the ocean currents, and then melt when they reach warmer waters.
The icebergs are very tricky and terrifying for the sailors, because in most cases, only small part of them is visible above the water, while a much bigger ice mass is hidden bellow the water. Because of that, lot of ships haven sunk over the years, with the most famous being the Titanic.
