Two waves are given by \[{{y}_{1}}=a\sin (\omega t-kx)\] and \[{{y}_{2}}=a\cos (\omega \,t-kx)\] The phase difference between the two waves is [MP PMT 1993; SCRA 1996; CET 1998; EAMCET 1991; Orissa JEE 2002]

• A.            \[\frac{\pi }{4}\]                 
• B.            p
• C.            \[\frac{\pi }{8}\]                 
• D.            \[\frac{\pi }{2}\]