A source that is moving emits sound at a frequency of $1200\text{ Hz}$. A stationary observer receives sound at a frequency of $960\text{ Hz}$. The speed of sound is $340\text{ m s}^{-1}$. What could be the velocity of the source?
- A$68\text{ m s}^{-1}$ directly away from the observer
- B$68\text{ m s}^{-1}$ directly towards the observer
- C$85\text{ m s}^{-1}$ directly away from the observer
- D$85\text{ m s}^{-1}$ directly towards the observer