The electronic configuration of an element with the largest difference between the $1^{\text {st }}$ and $2^{\text {nd }}$ ionization energies is

• A

  $1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6}$
• Correct answer
  B

  $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{1}$
• C

  $1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2}$
• D

  $1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{1}$

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