If $$\lambda_{Cu}$$ is the wavelength of $$K_{\alpha}$$ X-ray line of copper (atomic number 29) and $$\lambda_{Mo}$$ is the wavelength of the $$K_{\alpha}$$ X-ray line of molybdenum (atomic number 42), then the ratio $$\frac{\lambda_{Cu}}{\lambda_{Mo}}$$is close to

A

1.99

B

2.14

C

0.50

D

0.48