Answer:
the answer the correct one is B
Explanation:
The interference phenomenon is described by
d sin θ = m λ
The spectrum is recorded on a screen, so we can use trigonometry
tan θ = y / L
In this experiment the angles are very small, so
tan θ = sin θ /cos θ = sin θ
We replace
d y / L = m La m
y = m Lam L / d
When the slits approach the screen the value of L decreases,
Therefore the value of the separation between the slits must also decrease
When reviewing the answer the correct one is B