A wave represented by the given equation $y=A \sin \left(10 \pi x+15 \pi t+\frac{\pi}{3}\right)$ where $x$ is in meter and $t$ is in second. The expression represents
(a) A wave travelling in the positive $x$-direction with a velocity of $1.5 \mathrm{~m} / \mathrm{sec}$
(b) A wave travelling in the negative $x$-direction with a velocity of $1.5 \mathrm{~m} / \mathrm{sec}$
(c) A wave travelling in the negative $x$-direction with a wavelength of o.2 $m$
(d) A wave travelling in the positive $x$-direction with a wavelength of $0.2 \mathrm{~m}$