Answers:
a) Function
b) Domain = {3, -4, -3}
You won't type in the curly braces for the domain, but it's common to use them to indicate we're talking about a set.
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Explanation:
We have a function because each item in the domain (blue oval) goes to exactly one item in the range (green oval). We don't have two arrows or more originating from one item in the domain. So each input leads to exactly one output.
The domain is the set of allowed inputs. So the domain is the set {3, -4, -3}. Those items are found in the blue oval. As your teacher instructs, you won't be typing in the curly braces, but it's common to see the domain listed as a set like this. Optionally you can sort the items from smallest to largest, but it's not necessary. This is because order doesn't matter in a set.
