The correct answer is option C
The major ion in the sea water would be chloride. The reason is that the sea water is made of salt-water. The salt water is composed of sodium chloride.
The Chloride ion is found in the sea water in the form of Cl⁻ ion, it is one of the major inorganic ion found in seawater and freshwater.
It is formed by the dissociation of salts such as calcium chloride or sodium chloride in water.
