If the magnetic dipole moment of an atom of diamagnetic material,paramagnetic material,and ferromagnetic material are denoted by $\mu_d, \mu_p, \mu_f$ respectively,then:

• A
  $\mu_d \neq 0$ and $\mu_f \neq 0$
• B
  $\mu_p = 0$ and $\mu_f \neq 0$
• C
  $\mu_d = 0$ and $\mu_p \neq 0$
• D
  $\mu_d \neq 0$ and $\mu_p = 0$