I think you mean

f(x)= Sqrt (x-1) becasue none of them are f(x)= Sqrt x-1

f(x)= Sqrt (x-1)

you know Sqrt (4) = 2

and

f(x)= Sqrt (5-1)=sqrt(4)

so lets think about x=5

f(5)= sqrt(5-1) = sqrt4 = 2

So (5,2) must be a point on the graph.

So which is the correct graph?