Final answer:
Professional barbers traditionally use a straight razor alongside warm lather, which is created from various types of shaving creams to soften hair and provide lubrication for a precise shave.
Step-by-step explanation:
When professional barbers perform shaving services, they typically use warm lather and a conventional C) Straight razor. The warm lather, which could be made from a variety of shaving creams, serves the purpose of softening the hair and providing lubrication for a smooth shave. Shaving creams come in different types which include aerosol foam, brushless, and lather versions. The lather is often achieved with the use of a shaving brush and a lather shaving cream or shaving soap.
Shaving creams consist of an emulsion of oils, soaps, or surfactants like triethanolamine stearate and water. A lather shaving cream includes a humectant, which maintains moisture in the lather to create a softer consistency. This quality is particularly important when a barber is using a straight razor, as it demands a close and precise shave, which is facilitated by a good lather. In contrast, a brushless cream, which doesn't produce lather, contains an oil-in-water mixture. This variety is not traditionally used with straight razors in the same capacity as lather shaving cream in professional barbering.