The amplitude of a wave in a string is $2 \mathrm{~cm}$. This wave is propagating along the $\mathrm{x}$ -direction with a speed of $128 \mathrm{~m} / \mathrm{s}$. Five such waves are accommodated in $4 \mathrm{~m}$ length of the string. The equation for this wave is
(A) $\mathrm{y}=0.02 \sin (15.7 \mathrm{x}-2010 \mathrm{t}) \mathrm{m}$
(B) $\mathrm{y}=0.02 \sin (15.7 \mathrm{x}+2010 \mathrm{t}) \mathrm{m}$
(C) $\mathrm{y}=0.02 \sin (7.85 \mathrm{x}-1005 \mathrm{t}) \mathrm{m}$
(D) $\mathrm{y}=0.02 \sin (7.85 \mathrm{x}+1005 \mathrm{t}) \mathrm{m}$