In a glass block, light moves with a speed of $2.0 \times 10^{8}\,\text{m s}^{-1}$. The wavelength of the light in the glass is $4.0 \times 10^{-7}\,\text{m}$. Calculate the frequency of the light.
- A$2.0 \times 10^{-15}\,\text{Hz}$
- B$1.3 \times 10^{-2}\,\text{Hz}$
- C$80\,\text{Hz}$
- D$5.0 \times 10^{14}\,\text{Hz}$