A wave in a string has an amplitude of 2 cm. The wave travels in the + ve direction of x axis with a speed of 128 m/sec and it is noted that 5 complete waves fit in 4 m length of the string. The equation describing the wave is (a) y = (0.02) m sin (15.7x - 2010t) (b) y = (0.02) m sin (15.7x + 2010t) (c) y = (0.02) m sin (7.85x - 1005t) (d) y = (0.02) m sin (7.85x + 1005t)