The displacement $$y$$ of a particle in a medium can be expressed as $$y = 10^{-6} \sin(110t + 20x + \pi/4)$$ m, where $$t$$ is in seconds and $$x$$ in meter. The speed of the wave is

A

$$2000$$ m/s

B

$$5$$ m/s

C

$$20$$ m/s

D

$$5\pi$$ m/s