The equation of a plane progressive wave is y = 0.9 sin 4Ï€ [t - x^2], when it is reflected at a rigid support, its amplitude becomes 2/3 of its previous value. The equation of the reflected wave is:
A. y = 0.9 sin 4Ï€[t + x^2]
B. y = -0.6 sin 4Ï€[t + x^2]
C. y = 0.9 sin 8Ï€[t - x^2]
D. y = 0.6 sin 4Ï€[t + x^2]