Carbon dioxide in water is an example of a gas-liquid solute-solvent combination. In this case, carbon dioxide (CO2) is the solute, which is a gas, and water (H2O) is the solvent, which is a liquid. When carbon dioxide dissolves in water, it forms a solution where the gas is uniformly distributed within the liquid.
This combination is commonly seen in carbonated beverages, where carbon dioxide gas is dissolved in water under pressure, creating the fizzy effect. The correct answer is a) gas-liquid.