[" A plane wave "y=a sin(bx+ct)" is incident on a surface.Equation of the reflected wave is "y'=a'sin(c-b)],[" Which of the following statements is not correct? "],[" (A) The wave is incident on the surface normally."],[" (B) Reflecting surface is "y-z" plane."],[" (B) Reflecting surface is "y-z" plane."],[" (E) Medium,in which incident wave is travelling,is denserthan the other medium."]