____ are liquid preparations that contain one or more chemical substances dissolved in a suitable solvent or mixture of mutually miscible solvents.

• A. Suspensions
• B. Emulsions
• C. Gels
• D. Solutions

Answer: (D)

Solutions are liquid preparations in which one or more chemical substances are dissolved in a suitable solvent, or in a mixture of mutually miscible solvents. In a true solution, the drug is distributed at the molecular or ionic level, giving a single, homogeneous liquid. This is different from a suspension, which contains undissolved solid particles that may settle; from an emulsion, where one liquid is dispersed as droplets in another immiscible liquid; and from a gel, where liquid is immobilized within a gel network as a semisolid. So the description fits a solution because it emphasizes dissolution into a single, uniform phase.