The correct answer is A. Red Sea.
The Red Sea is the saltiest sea in the world, with an average salinity of 41 grams per liter. This is due to the fact that the Red Sea is a closed sea, meaning that it does not have any connection to the ocean. As a result, the water in the Red Sea is not able to be diluted by fresh water from the ocean.
The Dead Sea is the second saltiest sea in the world, with an average salinity of 33.7 grams per liter. The Dead Sea is so salty because it is located in a desert region and receives very little rainfall. As a result, the water in the Dead Sea evaporates very quickly, leaving behind a high concentration of salt.
The Arabian Sea is the third saltiest sea in the world, with an average salinity of 35 grams per liter. The Arabian Sea is salty because it is connected to the Indian Ocean, which is the saltiest ocean in the world.
The Mediterranean Sea is the fourth saltiest sea in the world, with an average salinity of 38 grams per liter. The Mediterranean Sea is salty because it is a closed sea, meaning that it does not have any connection to the ocean. As a result, the water in the Mediterranean Sea is not able to be diluted by fresh water from the ocean.