7.The inventor of spectacles probably lived in the town of Paris, Italy, around 1286, and was almost certainly a craftsman working in glass. But nobody knows his name. We only know this much about him because Friar Giordane preached a sermon one Wednesday morning in February 1306 at a church in Florence. "It＇s not yet 20 years since there was found the art of making eye-glasses which make for good vision," said the Friar."One of the best arts and most necessary that the world has. So short a time is it since there was invented a new art that never existed. I have seen the man who first invented and created it, and I have talked to him." We know what Friar Giordane said because admirers copied his sermons down as he gave them. The inventor of spectacles apparently kept the method of making them to himself. Perhaps he thought this was the best way of getting money from his invention. But the idea soon got around. As early as 1300, craftsmen in Venice,the centre of Europe＇s glass industry, were making the new "disks for the eyes".Spectacles at first were only shaped for far-sighted people. Concave lenses, for short-sighted people, were not developed until the late 15th century. Spectacles allowed people to go on reading and studying long after bad eyesight would normally have forced them to give up.They were like a new pair of eyes. The inventor of such a valuable thing should be honored, everyone thought. But for centuries no one had any idea who the inventor really was. So all kinds of candidates were put forward: Dutch, English, German, Italians from rival cities. A fake memorial was erected last century in a church in Florence to honor a man as the true inventor of spectacles-but he never even existed. 问题：The final paragraph discusses ( )

A. the function of spectacles

B. the fake memorial

C. the invention of spectacles

D. the identity of the inventor