(A) : According to Laplace the propagation of sound in air is an adiabatic process.
(B) : Pressure has no effect on velocity of sound in a gas as long as temperature remains constant.
(C) : The velocity of sound in air changes by 0.61 m/s when temperature changes by 1^oC.

(A) : According to Laplace the propagation of sound in air is an adiabatic process. $v=\sqrt{\frac{\gamma RT}{M}}$
(B) : Pressure has no effect on velocity of sound in a gas as long as temperature remains constant.
(C) : The velocity of sound in air changes by 0.61 m/s when temperature changes by 1^oC.

$\frac{v}{v_0}=\sqrt{\frac{T}{273}}=\sqrt{\frac{273+t}{273}}$

$v=v_0\sqrt{1+\frac{t}{273}}=v_0\left(1+\frac{t}{546}\right)$

$\text{ Since }{v}_0=332{ \mathrm{ms}}^{-1}\text{ at }0°C\text{, v at a particular temperature in }t°\mathrm{C}\text{ is }$

$v=(332+0.61t)m{s}^{-1}$