Final answer:
The dizi is the instrument featured in the 12 Girls Band that is a flute. It is known for its bright sound and is used in various musical settings, unlike the guzheng, erhu, and yangqin which are stringed and percussion instruments.
Step-by-step explanation:
The instrument from the 12 Girls Band that is a flute is B. dizi. The dizi is a traditional Chinese woodwind instrument, which is known for its pure, bright sound, and is often used in both solo and ensemble pieces. On the other hand, A. guzheng is a Chinese plucked string instrument, C. erhu is a two-stringed bowed instrument, and D. yangqin is a hammered dulcimer.