Could someone please explain this?

The support for (E) comes at the in the last paragraph. Venetian painters didn’t paint frescos, so they didn’t learn how to draw human figures as well as Tuscan painters could (lines 49-57). Instead, “painting architecture in perspective was seen as a particular test of the Venetian painter's skill” (lines 64-65). So, they learned how to paint buildings in perspective really well, which is why we see so many “elaborate buildings” in their paintings (lines 10).