Answer:
The width of the central bright fringe becomes narrower.
Step-by-step explanation:
In case of Single Slit, diffraction will occur.
Then In Single slit Diffraction, width of central fringe is

where D= distance between screen and slit
a= slit width

Thus if Screen width increases keeping other factors same then width of cental fringe becomes narrower as

The width of the central bright fringe becomes narrower.