According to moselay’s law, the frequency ($\nu$) of the $K_{\alpha }$  line and the atomic number (z) of the element have the relation (C is a constant)

• A

  $\nu$α(z–c)

• B

  $\nu$α(z–c)²

• C

  $\sqrt{\nu }\infty$(z–c)²

• D

  $\nu \infty \frac{1}{{\left(z-c\right)}^2}$