The screen of a cathode-ray oscilloscope shows the output from an electronic circuit. The time-base is adjusted to $5.0\,\text{ns}$ per division and the Y-gain to $10\,\text{V}$ per division. What is the frequency of the signal?
- A$2.0 \times 10^{8}\,\text{Hz}$
- B$2.5 \times 10^{7}\,\text{Hz}$
- C$5.0 \times 10^{7}\,\text{Hz}$
- D$3.1 \times 10^{8}\,\text{Hz}$