${y_1} = 10\,\sin \,200\pi t$,
${y_2} = 20\,\sin \,\left( {2000\pi t + \frac{\pi }{2}} \right)$
are superimposed at any point at a particular instant. The amplitude of the resultant wave is
| $(A)$ Temperature of gas is made $4$ times and pressure $2$ times | $(P)$ speed becomes $2\sqrt 2$ times |
| $(B)$ Only pressure is made $4$ times without change in temperature | $(Q)$ speed become $2$ times |
| $(C)$ Only temperature is changed to $4$ times | $(R)$ speed remains unchanged |
| $(D)$ Molecular mass of the gas is made $4$ times | $(S)$ speed remains half |