A miniature loudspeaker, starting from rest, drops vertically from a window in a tall building. After it has fallen a distance of $10.0\,\text{m}$, it emits a very brief sound pulse with constant frequency $256\,\text{Hz}$ in all directions. The sound pulse, moving at a speed of $330\,\text{m s}^{-1}$, is detected by a person leaning out of the window. Air resistance is negligible. What frequency is heard by the person for the sound pulse?
- A$246\,\text{Hz}$
- B$249\,\text{Hz}$
- C$267\,\text{Hz}$
- D$313\,\text{Hz}$