A linear aperture whose width is $\mathrm{0.02\; cm}$ is placed immediately in front of a lens of focal length $\mathrm{60\; cm.}$ The aperture is illuminated normally by a parallel beam of wavelength $5\times {10}^{-5}\mathrm{ }\mathrm{c}\mathrm{m}$. The distance of the first dark band of the diffraction pattern from the centre of the screen is

• A

  $0.10\text{cm}$
• B

  $0.25\text{cm}$
• C

  $0.20\text{cm}$
• Correct answer
  D

  $0.15\text{cm}$

Hence, the correct answer is option: 'D'.