In the context of string instruments, what does the term "bowing" refer to?

Bowing refers specifically to the technique of producing sound on string instruments, such as violins, cellos, and violas. This technique involves using a bow, which is a flexible stick with horsehair stretched between its ends, to create vibrations in the strings. When the bow is drawn across the strings, it causes them to vibrate, producing musical notes. This action is integral to playing string instruments, as it allows for a range of dynamics, articulations, and expressiveness in the music.

The other options, while related to string instruments, do not capture the essence of "bowing." The use of strings is fundamental to string instruments, but it is not specific to bowing. Changing pitch involves techniques such as finger placement and adjusting the tension on the strings, which are separate from the act of bowing itself. Holding the instrument is crucial for playing, but it does not pertain to the method of sound production that bowing represents. Hence, the primary focus of bowing is correctly identified as the technique of producing sound.