Allegro D-major, KV 334, arranged for Transverse Flute, Violin and Viola
or 2 Violins and Viola from the Divertimento KV 334 (Terzett) http://music-learning.net/work-info/41/Mozart%20W.a./allegro-d-major-kv-334-arranged-for-transverse-flute-violin-and-viola