Number of photons having wavelength $\text{632}\text{.8}\text{nm,}$ emitted by $\text{5}\text{mW}$ laser source in $\text{1}$ second is

• A

  $1.6\times 10^{19}$
• Correct answer
  B

  $1.6\times 10^{16}$
• C

  $1.6\times 10^{25}$
• D

  $1.6\times 10^{13}$

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