A pendulum has time period $T$ for small oscillations. An obstacle $\mathrm{P}$ is situated below the point of suspension $\mathrm{O}$ at a distance $\frac{3l}{4}$. The pendulum is released from rest. Throughout the motion the moving string makes small angles with vertical. Time after which the pendulum returns back to its initial position is -

• A

  $T$
• Correct answer
  B

  $3T/4$
• C

  $3T/5$
• D

  $4T/5$

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