The vertical displacement due to a travelling wave moving horizontally is given by y(x,t) = 5.4cos(.4(rad/s) t (sec)) where x and y are in centimeters. The horizontal distance between the points whose phase differs by pi/3 is A. 1.05 cm B. 2.62 cm C. 7.86 cm D. 9.81 cm E. 13.6 cm