The output from a signal generator is linked to a cathode-ray oscilloscope (CRO). A trace appears on the screen. The CRO time-base is set to $2.00\,\text{ms cm}^{-1}$. What is the frequency of the signal?
- A$50\,\text{Hz}$
- B$125\,\text{Hz}$
- C$250\,\text{Hz}$
- D$500\,\text{Hz}$