How can fringe width increase in Young's double slit experiment?

by reducing the separation of the slits

The correct answer is Option (4) → by reducing the separation of the slits

In young's Double slit experiment, the fringe width (β) is -

$β=\frac{λD}{d}$

$λ$ → Wavelength of light

D → Distance between screen and slits

d → Distance between two slits

∴ On reducing the separation between the slits fringe width (β) can be increased.