What technique in violin playing is known as 'double-stopping'?

The technique known as 'double-stopping' in violin playing refers to the ability to play two notes simultaneously. This technique involves drawing the bow across two strings at the same time, allowing for the creation of harmonies and richer textures in the music. Double stopping is commonly used in various musical styles, enabling the performer to add depth to the melody.

The ability to produce two distinct pitches concurrently allows composers and musicians to explore more complex musical ideas, contributing significantly to the overall sound of a piece. It can be found in classical, folk, and contemporary styles, showcasing the versatility of the violin.

The other techniques listed involve different aspects of violin performance, such as harmonics, varied bow strokes, or sustained single notes, which do not encompass the essence of playing two notes at once. Therefore, the correct identification of double-stopping as playing two notes simultaneously highlights its fundamental role in string performance and music composition.