One to one means only one x value gives one y value
This only happens when x is greater than or equal to -1 [-1, infinity) or when x is less than or equal to -1 (-infinity, -1].
Non decreasing means the slope is zero or positive, so it has to be the first option for the domain [-1, infinity]
The inverse of f(x) = (x + 1)^2
y = (x + 1)^2
x = (y + 1)^2
Sq rt x = y + 1
(sq rt x) - 1 = y
f^-1(x) = (sq rt x) - 1
We cannot take the square root of -1, so the domain of the inverse of f is [0, infinity]