A laser beam can be focused on an area equal to the square of its wavelength. A He-Ne laser radiates energy at the rate of 1 mW and its wavelength is 632.8 nm. The intensity of focused beam will be

• A

  $1.5\times {10}^{13} \mathrm{W}/{\mathrm{m}}^2$

• B

  $2.5\times {10}^9 \mathrm{W}/{\mathrm{m}}^2$

• C

  $3.5\times {10}^{17} \mathrm{W}/{\mathrm{m}}^2$

• D

  None of these