A wave travelling along the $x$ - axis is described by the equation $y(x,t) = 0.005\: \cos(\alpha x - \beta t)$. If the wavelength and time period of the wave are $0.08 \: m$ and $2\: s$, respectively, then $\alpha$ and $\beta$ in appropriate units are

Question

$\begin {array} {1 1} (a)\;\alpha = 25 \pi, \beta = \pi & \quad (b)\;\alpha = \large\frac{0.08}{\pi}, \beta = \large\frac{2}{ \pi} \\ (c)\;\alpha = \large\frac{0.04}{ \pi}, \beta = \large\frac{1}{ \pi} & \quad (d)\;\alpha = 12.5 \pi, \beta = \large\frac{\pi}{2} \end {array}$