7. When we blow across the mouth of a bottle, we can cause a standing wave in the air inside the bottle, which makes a musical sound. Blowing harder can give a higher musical pitch, but that takes practice. Assume that, for any liquid height in the bottle, we can reliably obtain only the fundamental (first harmonic) and the next higher harmonic frequency by blowing. Consider a beverage bottle 25 cm in length, with an original liquid height of 20 cm inside (before we drink any of the beverage). Given that the speed of sound in air is 343 m/s, what range of frequencies can you obtain as you slowly sip the liquid in the bottle? (Choose the closest match.) (A) 20 – 20000 Hz. (B) 80 – 13500 Hz. (C) 350 – 5000 Hz. (D) 1200 – 3600 Hz.