Could someone please explain this?

The author’s claim that Venetian artists “had no practical experience of the large-scale representation of familiar religious stories” is based on evidence that Venice was too damp for large-scale frescoes and that narrative frescoes in churches were nonexistent. The problem with this argument is that even if Venice couldn’t feature large-scale fresco paintings that depicted familiar religious stories, Venetian artists could still have experience with large-scale fresco paintings that depicted familiar religious stories. Especially if they left Venice and went to a place that featured such paintings. This is why (C) is the correct answer.