Faradic current is primarily used in beauty therapy for its ability to stimulate muscle contraction, making it an effective tool for muscle toning and rehabilitation. This type of current helps in activating the motor nerves, leading to involuntary contractions of the muscles. This stimulation is particularly beneficial in beauty treatments aimed at strengthening and training specific muscle groups, which can improve muscle tone and contour the appearance of the body.
In contrast, galvanic current is mainly used for iontophoresis and chemical reactions that assist in product penetration and conductivity in the skin, rather than for muscle stimulation. Therefore, while galvanic current might have its own specific applications, faradic current's unique capability to facilitate muscle training stands out as its primary strength in beauty therapy.
Choosing the option related to muscle effectiveness appropriately aligns with the established uses and benefits of faradic current in aesthetic treatments, distinguishing it from galvanic current and making it the correct answer in this context.