The answer is B. The less massive object to orbit the more massive object.
Explanation: The more massive the object, the larger its gravitational pull.
Example: the moon orbits the earth because the moon’s mass is smaller than earth, earth orbits the sun because the earth’s mass is smaller than the sun..
When air is blown into the open pipe,
L = 
where nis any integral number 1,2,3,4 etc. and λ is the wavelength of the oscillation
⇒λ=
Note here that n=1 is for fundamental, n=2 is first harmonic and so on..
⇒ third harmonic will be n=4
Given L=6m, n=4, solving for λ we get:
λ=
=3m
Relationship of frequency(f), velocity of sound (c) and wavelength(λ) is:
c=f.λ Or f= 
⇒f=
≈115 Hz
Answer:
distance must be = 330 × 5/2
= 330×2.5
=825m