Answer:
Option D.
Explanation:
We have the function:
f(x) = -a*(x + b)^(1/2)
Where:
a > 0
b > 0
Now, as a is positive and we have the coefficient "-a", we will have that the function is always negative.
Why? because (x + b)^(1/2) is always positive.
then: -a*(x + b)^(1/2) is always negative.
We also should see that the domain is not the set of all real numbers, because if:
x + b < 0, then we have the square root of a negative number, and we know that this is a complex number.
The only option that meets these two conditions is option D.