In an experiment on photoelectric effect on a metal surface, one finds a stopping potential of $$1.8\,\text{V}$$ for the wavelength of $$300\,\text{nm}$$ and a stopping potential of $$0.9\,\text{V}$$ for the wavelength of $$400\,\text{nm}$$. The cutoff wavelength $$\lambda_0$$, the maximum wavelength that can produce photoelectric effect, for the metal is

A

$$500\,\text{nm}$$

B

$$550\,\text{nm}$$

C

$$600\,\text{nm}$$

D

$$750\,\text{nm}$$