Which of the following is not true about Galileo?

AHe was such a brilliant mathematician that he became a professor of mathematics at the age of 25.

BHe developed a new and improved thermometer and a better compass.

CHe designed a telescope 10 times more powerful than earlier models.

DHe was able to prove that Ptolemy's theory that the moon had a smooth, polished surface was true.

EAt the Inquisition he signed a paper taking back his radical ideas about the Earth revolving around the sun.