A #"standard solution"# is #"aqueous"#, #"unsaturated"#, #"a mother solution"#?
None of your options is satisfactory........
A solution of known concentration, may be
and typically we report the concentration with units of
Should be "Standard solution", shouldn't it?
None of the other possible answers work.
"Normal" means unit gram equivalent mass of solute per litre of solution.
"Aqueous" just means that the solvent is water.
"Original" means that a solution used to prepare other solutions by dilution.
"Unsaturated" means that the amount of solute dissolved is below the maximum amount that can be dissolved per unit volume.
"Standard solution" = a solution that contains a precisely known concentration of solute (in analytical terms anyway).