A parallel beam of white light is directed normally at a diffraction grating. The second-order and third-order spectra overlap partly. Which wavelength in the third-order spectrum is seen at the same angle as the wavelength of $600\,\text{nm}$ in the second-order spectrum?
- A$300\,\text{nm}$
- B$400\,\text{nm}$
- C$600\,\text{nm}$
- D$900\,\text{nm}$