Answer Choice 1
Take it step by step!
First find what sqrt(x-7) is like. Compare it to sqrt(x).
You can see that in sqrt(x), when x = 0, y = 0. However, in sqrt(x-7), when x = 7, y = 0. When y = 0, sqrt(x-7) is 7 more, which means it is shifted 7 units to the right.
Similarly, +8 means that whatever sqrt(x-7) is, you add 8 more to y. Adding on extra for y is just moving it up by 8 units.
Hope that helped,
-sirswagger21