A pharmacy technician is preparing to measure a liquid. Which of the following pieces of equipment should the technician select for this task?

The graduated cylinder is the best choice for measuring a liquid accurately. It is specifically designed for precise measurement and has markings along its side that allow for exact readings of volume. This precision is crucial in pharmacy practice where exact dosages of liquids are often needed to ensure patient safety and efficacy of medications. The narrow shape of the graduated cylinder minimizes the impact of meniscus formation, which is essential for accurate volume measurement.

While beakers, mortars and pestles, and Erlenmeyer flasks are useful in a laboratory setting, they are not as suited for precise volume measurements. Beakers are generally used for mixing and pouring rather than for accuracy, while a mortar and pestle are more commonly used for grinding solid substances. Erlenmeyer flasks, although useful for mixing, do not provide the level of precision required for measuring specific liquid volumes. Thus, the graduated cylinder stands out as the most appropriate equipment for this task.