What does this mean exactly?

Choice B  

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Explanation:

They want to know what are all the possible y values here. The range is the set of all possible outputs of a function.

The largest y value is y = 0 which occurs at the vertex, in this case the highest point. There is no smallest y value as those arrows point downward forever.

So y is between negative infinity and 0, which means we write

Converting that to interval notation leads to . Note the square bracket to include the endpoint.

The compound inequality simplifies to

One way to describe this particular relation's range is to say "The set of negative real numbers with 0 included".

Side note: The domain is the set of all possible x inputs. In this case, the domain is the set of all real numbers.

expression #3 is not equivalent. the others are.