The diameter of the objective of a telescope is a,  its magnifying power is m and wavelength of light is $\mathrm{\lambda }$. The resolving power of the telescope is

• A

  $(1.22\mathrm{\lambda })/\mathrm{a}$

• B

  $(1.22\mathrm{a})/\mathrm{\lambda }$

• C

  $\mathrm{\lambda m}/(1.22\mathrm{a})$

• D

  $a/(1.22\lambda )$