(c) In the fundamental mode of vibration
$\frac{\lambda}{4} = (l + 0.3d)$
Where 0.3d the necessary end correction. frequency of vibration,
$v = \frac{v}{\lambda} = \frac{v}{4(l + 0.3)}$
As 𝒍 is same for both pipes, wider pipe (A) will resonate at a lower frequency, i.e., $v_{A} < v_{B}.$