When a wave traverses a medium , the displacement of a particle located at $'x'$ at a time $'t'$ is given by $y=a \sin (bt-cx), where a,b and c are constants of the wave, which of the following is a quantity with dimensions?

Question

$$\begin {array} {1 1} (1)\;y/a & \quad (2)\;bt \\ (3)\;cx & \quad (4)\;b/c \end {array}$$