The path difference between the two waves
`y_(1)=a_(1) sin(omega t-(2pi x)/(lambda)) and y(2)=a_(2) cos(omega t-(2pi x)/(lambda)+phi)` is
A. `(lambda)/(2pi) phi`
B. `(lambda)/(2pi) ( phi+(pi)/(2))`
C. `(2pi)/(lambda) (phi-(pi)/(2))`
D. `(2pi)/(lambda) phi`