A mass of $\mathrm{M} \mathrm{kg}$ is suspended by a weightless string. The horizontal force that is required to displace it until the string makes an angle of $45^{\circ}$ with the initial vertical direction is

• Correct answer
  A

  $M g(\sqrt{2}-1)$
• B

  $M g(\sqrt{2}+1)$
• C

  $M g \sqrt{2}$
• D

  $\frac{\mathrm{Mg}}{\sqrt{2}}$

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