An observer is positioned at the summit of a tall tower. An aeroplane that is emitting sound with a frequency of $1000\,\text{Hz}$ moves towards the observer at a speed of $165\,\text{m s}^{-1}$. The speed of sound is $330\,\text{m s}^{-1}$. What frequency does the observer receive for the sound?
- A$330\,\text{Hz}$
- B$667\,\text{Hz}$
- C$1000\,\text{Hz}$
- D$2000\,\text{Hz}$