The correct option is C $$Range=16.5m-16.5 mm$$
According to question, Temperature is constant and other surroundings are constant (gas,pressure etc...).
$$\implies$$ Formula for Velocity of Sound remain same i.e., $$v=u\lambda$$ , where $$v$$ is the speed of sound, $$u$$ is the frequency and $$\lambda$$ is the wavelength of sound.
Velocity of Sound remains constant i.e., $$v=330m/s$$ (# According to question given)
Range of Frequency$$(u)$$ given, $$20- 20000$$ Hz
And, $$\lambda = v/u$$
$$\implies$$ Range of Wavelength$$(\lambda _R)$$ is, $$330/20 - 330/20000\cong 16.5m - 16.5mm$$
$$\implies$$ $$Range = 16.5m - 16.5mm$$
Therefor, answer is option C.