A microphone picks up a musical sound, and the resulting signal is sent to an oscilloscope. The diagram shows the trace that is displayed on the screen. The spot of light on the oscilloscope screen takes $1.2\ \text{ms}$ to move from one side to the other. What is the frequency of the musical sound?
- A$170\ \text{Hz}$
- B$330\ \text{Hz}$
- C$1700\ \text{Hz}$
- D$3300\ \text{Hz}$