Two billiard balls of equal mass $30 \mathrm{g}$ strike a rigid wall with same speed of $108 \mathrm{kmph}$ (as shown) but at different angles. If the balls get reflected with the same speed, then the ratio of the magnitude of impulses imparted to ball $a$ and ball $b$ by the wall along $X$ direction is:

• A

  $1:1$
• Correct answer
  B

  $\sqrt{2}:1$
• C

  $2:1$
• D

  $1:\sqrt{2}$

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