What is the primary use of a dropper?

The primary use of a dropper is to move small amounts of liquids, which is essential in various settings, particularly in healthcare and laboratory environments. Droppers allow precise delivery of liquid solutions or medications, making them highly effective for tasks such as administering exact dosages of medications, adding reagents in experiments, or transferring samples without spillage. This precision is key for safety and efficacy when dealing with sensitive tasks that require careful handling of liquids.

Considering the other options, measuring solid substances would not be an appropriate use for a dropper, as its design is not suited for solids. Providing electrical stimulation is completely outside the function of a dropper, as it is a manual tool intended for liquid transfer. Alleviating discomfort may refer to a broader range of applications involving medications or therapies, but it does not specifically pertain to the primary function of moving liquids, which is the defining characteristic of a dropper.