Which one of the following can be categorised as a solution?

The correct answer is option 4. Sea Water.

The substance that can be categorized as a solution among the options is Sea Water.

A solution is a homogeneous mixture composed of two or more substances, where one substance (the solute) is uniformly distributed in another substance (the solvent). In the case of sea water, it is a solution where various salts and minerals are dissolved in water, making it a homogeneous mixture.