Answer:
Option (1)
Explanation:
Relation between wavelength and frequency of a wave is,
Wavelength (λ) ∝ [tex]\frac{1}{\text{Frequency}}[/tex]
That means wavelength is inversely proportional to the frequency of a wave.
When the wavelength of the wave is decreased, frequency of the wave will increase.
Therefore, if the distance across section 1 is decreased in the given picture,
wavelength gets decreased.
As a result frequency of the wave will increase.
Option (1) will be the answer.
