Question

What is the range of the function in the graph?

Answer 1

Locate the highest or lowest point on the graph. In this case, there is no highest point. There is only the lowest point. That lowest point is (2,0). 

The y coordinate of that lowest point is y = 0. This is the smallest y can be. The value of y cannot be any smaller. This forms the left boundary of the interval notation answer.

There is no upper boundary on how high y can go. It can grow forever. Therefore the right boundary of the interval is infinity

This is why the answer is the interval notation answer $[0,\infty)$
The square bracket indicates "include this value in the set" while a parenthesis says "exclude this value". We can never reach infinity so infinity is always with a parenthesis

Final Answer: Choice A

Note: the interval notation answer for choice A is the same as writing $y \ge 0$ (y is greater than or equal to 0)