Final answer:
To accurately deliver 20.00 ml of solution, a volumetric pipet is the best choice due to its design for delivering a single, precise volume. Graduated cylinders and burettes are less suitable for this single-volume delivery task.
Step-by-step explanation:
To accurately deliver 20.00 ml of solution, the best piece of glassware to choose is a volumetric pipet. Volumetric pipets are designed to deliver a single, precise volume of liquid when filled to the calibration mark. While a graduated cylinder can also measure volume, it is not as accurate as a volumetric pipet. Beakers are the least accurate for measuring volumes, and while a volumetric flask can accurately contain specific volumes, it is not designed to deliver volumes. For measurements requiring high precision, like in titrations, a burette could also be used, but if we're considering delivery rather than continuous measurement, the volumetric pipet is the ideal choice.