What practice involves the external application of water for therapeutic effects?

The correct answer is hydrotherapy because it specifically refers to the use of water in various forms, such as baths, pools, compresses, or steam, aimed at providing therapeutic benefits. This practice can help with relaxation, pain relief, and improved circulation, making it a valuable tool in wellness and rehabilitation.

Aromatherapy, while also a therapeutic practice, focuses on the use of essential oils and fragrances rather than water. Thermotherapy involves the application of heat to treat conditions but does not exclusively use water. Kinesiology relates to the study of body movement and is not a therapy centered around the application of water. Thus, hydrotherapy uniquely addresses the therapeutic effects derived from water use.