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
 Â
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