Answer: Choice A. f(x) = sqrt(x-1)
===========================================
Step-by-step explanation:
The parent function is y = sqrt(x) and the left-most edge of this curve is at (0,0).
The graph shows the left-most point at (1,0) instead.
This means we've shifted everything 1 unit to the right, or you can think of the xy axis being shifted 1 unit to the left while the square root curve stays still (giving the illusion the curve moves).
If we shifted the xy axis 1 unit to the left, then each input x becomes one smaller, so each input is now x-1
That's why we go from y = sqrt(x) to y = sqrt(x-1)
You can use a graphing calculator to confirm this, or you can create a table of values to generate the points on this new blue curve.