The two waves represented by ${\mathrm{y}}_1=\mathrm{asin}\left(\mathrm{\omega t}\right)$ and ${\mathrm{y}}_2=\mathrm{bcos}\left(\mathrm{\omega t}\right)$ have a phase difference of

• A

  0

• B

  $\frac{\mathrm{\pi }}{2}$

• C

  $\mathrm{\pi }$

• D

  $\frac{\mathrm{\pi }}{4}$