What service involves temporarily removing facial hair one at a time?

The service that involves temporarily removing facial hair one at a time is tweezing. Tweezing is a common technique that uses a pair of tweezers to grasp individual hairs and pull them out from the root. This method allows for precise control and is particularly effective for shaping eyebrows and removing small areas of unwanted hair on the face.

While other methods mentioned, such as waxing, threading, and electrolysis, are also effective hair removal techniques, they differ in how they operate and the number of hairs they address at once. For instance, waxing removes multiple hairs at once, making it a quicker process for larger areas, while threading employs a twisted thread to trap and remove rows of hair simultaneously. Electrolysis is a permanent hair removal method that uses electrical currents to destroy hair follicles, but it also treats hairs one at a time. However, in the context of temporary removal, tweezing is specifically designed for individual hairs, making it the correct answer.