The correct option is B Syrinx
Syrinx is the name for the vocal organ of singing birds. Located at the base of a bird's trachea, it produces sounds without the vocal cords of mammals. The sound is produced by vibrations of some or all of the membrane tympaniformis (the walls of the syrinx) and the pessulus caused by air flowing through the syrinx. This sets up a self-oscillating system that modulates the airflow creating the sound. The muscles modulate the sound shape by changing the tension of the membranes and the bronchial openings. The syrinx enables some species of birds (such as parrots, crows, and mynas) to mimic human speech.