" A few genuine advances in understanding the hieroglyphs were made during the 1700s. The French scholar C. J. de Guignes observed that groups of hieroglyphs in Egyptian texts were often enclosed by an oval outline, which he called a cartouche. "Cartouche" is a French word that originally meant a cartridge, and the line around the hieroglyphs had a similar shape. De Guignes guessed rightly that the cartouches in hieroglyphic inscriptions were intended to draw attention to important names, probably the names of Egyptian rulers. " —The Riddle of the Rosetta Stone, James Cross Giblin

Which detail from the passage shows that James Cross Giblin agrees with de Guignes’s view of cartouches?
A. He calls it a genuine advance in understanding.
B. He uses the French word de Guignes uses.
C. He calls the discovery a guess.
D. He explains the cartouche in detail.