What is the frequency of light that has a wavelength of 249 nm?

What is the frequency of light that has a wavelength of 249 nm? hints what is the frequency of light that has a wavelength of 249 nm?

a. 1.20 × 106 sec?
b. 11.20 × 1015 sec?
c. 11.20 × 1015 sec
d. 1.20 × 10?3 sec?1?