C. Many people believed Champollion copied Young's idea that hieroglyphs represented sounds.
If you read the story about the Rosetta stone it states...For many years Champollion’s progress was blocked because, like de Sacy and earlier scholars, he believed the hieroglyphs represented things, not sounds. Then, in 1822, he reversed his position. Some of Champollion’s rivals suggested that he had gotten the idea from Thomas Young’s Encyclopedia Britannica article. There the English scholar explained how the hieroglyphs in Ptolemy’s name stood for sounds. Champollion hotly denied these suggestions, claiming that he had arrived at his new position entirely on his own. - The Riddle of the Rosetta Stone