Plucking a guitar string produces a longitudinal sound wave in the air, as illustrated. The speed of sound in air is $340\,\text{m s}^{-1}$. What is the approximate frequency of the sound wave shown?
- A$430\,\text{Hz}$
- B$680\,\text{Hz}$
- C$1100\,\text{Hz}$
- D$1400\,\text{Hz}$