For an aperture of $5 \times 10^{-3} \mathrm{~m}$ and a monochromatic light of wavelength $\lambda$, the distance for which ray optics becomes a good approximation is 50 m, then $\lambda=$

• Correct answer
  A

  $5000 Å$
• B

  $6000 Å$
• C

  $5400 Å$
• D

  $6500 Å$

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