Seawater is highly concentrated in salt, and with that being said, it has a low concentration of water molecules.
Hypertonic means the solution has a lower water concentration than the other side (cell), vice versa for hypotonic, a high water concentration than the other side of the solution, and for isotonic, it means that both sides of the solution have the same water concentration.
So, the answer should be 1, hypertonic.
In addition, when your cells are exposed to hypertonic solution, the water molecules in your cells will start flowing out of the cells, to the outside, due to the difference in water concentration leading to osmosis. Your cells will lose so much water that they may even shrink!
