No 12., 19,28 and 29.

i believe it's a.

i'm not sure on this one, most likely correct.

sample answer: you can determine whether each element of the domain is paired with exactly one element of the range. for example, if given a graph, you could use the vertical line test; if a vertical line intersects the graph more than once, then the relation that the graph represents is not a function.

i would say true? if the unit was informational and it "refreshed your understanding", then true.