A source producing sound with frequency $1000\,\text{Hz}$ travels away from an observer who is at rest at a speed of $30.0\,\text{m s}^{-1}$. The speed of sound is $330\,\text{m s}^{-1}$. What frequency of sound does the observer hear?
- A$909\,\text{Hz}$
- B$917\,\text{Hz}$
- C$1090\,\text{Hz}$
- D$1100\,\text{Hz}$