The right answer is "A solution" .
In chemistry, a solution is a homogeneous mixture (consisting of a single phase) resulting from the dissolution of one or more solute (s) (dissolved chemical species) in a solvent. The molecules (or ions) of solute are then solvated and dispersed in the solvent.
Pentothal is a medicinal product available in the hospital as a powder for solution for injection containing Thiopental Sodium (1 g).