Answer is: A. solute
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Solvation is the interaction of solvent (in this example water) with molecules or ions (in this example carbon dioxide)) in a solute.
Solvent (usually a liquid, but can also be a solid or a gas) is a substance that dissolves a solute (dissolved in the solvent).
Solvent is always the same state of matter as the solution. In this example, soft drink is a liquid, so water is a solvent.
