Final answer:
Calibration routines in chemistry are performed using a standard solution, which is a precisely known concentration of a solution made for calibration purposes.
Step-by-step explanation:
Calibration routines are performed using a standard solution, which is a specimen with a known value. Among the options provided, a standard solution, or stock solution, is a carefully prepared solution with precisely known concentrations used for calibration in chemistry experiments. It is made by dissolving a precise mass of a solute into a precise volume of solvent using lab equipment like a volumetric flask that is calibrated to a single volume. The process ensures a high degree of precision in subsequent measurements and experiments.