I'm assuming this is multiple choice and you forgot to post the answers. I'll take a guess and say it probably looks something like this:

Because you can't take the square root of a negative number without getting an imaginary result, resulting in the function having a closed domain limit.
I think it A... But if it not sorry I didn’t help... hope this is the answer I am sure it is...
Answer:
C. Both x is a function of y and y is a function of x
Step-by-step explanation:
A <u>function</u> is a relationship which assigns to each input (from the domain) value, a unique output (from the range).
y is a function of x means x is from domain, y is from range
x is a function of y means y is from domain, x is from range
1. Given 
y is a function of x because for each x there is exactly one y corresponding to this x.
2. Rewrite
expressing x in terms of y:

x is a function of y because for each y there is exactly one x corresponding to this x.
Answer: C
Step-by-step explanation:
The zeros of a graph are where the graph intersects the x-axis.