In a closed tube whose length can be altered by sliding one of the halves relative to other is shown in the figure. In the initial condition the detector detects minimum intensity. One of the tubes is then displaced by $5 \mathrm{cm}$, during this displacement detector detects maximum intensity for $10$ times and then a minimum intensity when the displacement is complete. What is the wavelength of sound?

• A

  $\text{10/9 cm}$
• Correct answer
  B

  $\text{1 cm}$
• C

  $1/2 \mathrm{cm}$
• D

  $5/9 \mathrm{cm}$

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