A wave is represented by the equation \[y=7\sin \left( 7\pi t-0.04\,x\pi +\frac{\pi }{3} \right)\] x is in metres and t is in seconds. The speed of the wave is [MP PET 1996; AMU (Engg.) 1999]

• A.            175 m/sec                              
• B.            49 pm/sec
• C.            49 pm/sec                             
• D.            0.28 pm/sec