If the speed of the wave shown in the figure is 330 m/s in the given medium, then the equation of the wave propagation in the positive x-direction will be ……………. (a) y = 0.05 sin 2π (4000t – 12.5x) m (b) y = 0.05 sin 2π (4000t – 122.5x) m (c) y = 0.05 sin 2π (3300t – 10x) m (d) y = 0.05 sin 2π (3300t – 10x) m