A ship’s siren is reflected off a cliff. A sailor standing on the deck hears an echo $4.0\,\text{s}$ after the siren is sounded. The speed of sound in air is $320\,\text{m}\,\text{s}^{-1}$. How far away from the cliff is the ship?
- A$80\,\text{m}$
- B$160\,\text{m}$
- C$640\,\text{m}$
- D$1280\,\text{m}$