A loudspeaker producing a steady frequency of $2000\,\text{Hz}$ is moved in a horizontal circle at a speed of $15.0\,\text{m s}^{-1}$. A stationary observer, positioned level with the loudspeaker and far away from it, hears sound whose frequency changes. The greatest frequency heard is $2097\,\text{Hz}$. Determine the speed of sound in air.
- A$294\,\text{m s}^{-1}$
- B$309\,\text{m s}^{-1}$
- C$324\,\text{m s}^{-1}$
- D$330\,\text{m s}^{-1}$