Two masses $M_1$ and $M_2$ are tied together at the two ends of a light inextensible string that passes over a frictionless pulley. When the mass $M_2$ is twice that of $M_1$. the acceleration of the system is $a_1$. When the mass $M_2$ is thrice that of $M_1$. The acceleration of The system is $a_2$. The ratio $\frac{a_1}{a_2}$ will be

• A

  $\frac{1}{3}$
• Correct answer
  B

  $\frac{2}{3}$
• C

  $\frac{3}{2}$
• D

  $\frac{1}{2}$

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