The displacement $\text{y}$ of a particle in a medium can be expressed as $\text{y}={\text{10}}^{-6}\text{sin}\left(\text{100}\mathrm{t}-\text{20x}+\mathrm{\pi }/4\right) \mathrm{m}$, where $\text{t}$ is in seconds and $\text{x}$ in meters. The speed of the wave is

• A

  $2000 \mathrm{m} {\mathrm{s}}^{-1}$
• Correct answer
  B

  $5 \mathrm{m} {\mathrm{s}}^{-1}$
• C

  $20 \mathrm{m} {\mathrm{s}}^{-1}$
• D

  $5\mathrm{\pi } \mathrm{m} {\mathrm{s}}^{-1}$

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