Answer:
The conclusion that the act supports is that the American Government wanted very few immigrants compared to the previous decades, and that they wanted the majority of those immigrants to come from northern European countries like Germany, Great Britain, and Scandinavia.
As we can see, Italy does not even show in the list, and it had been one of the largest soucers of immigration in the previous decades. The government not only wanted restrict all immigration, but specially immigration from southern Europe and from Asia.
