One of the French experts, Sylvestre de Sacy, started with the proper names in the Greek passage and tried to find their equivalents in the demotic version. He believed that, after he’d sin­gled out the names, he would be able to identify the demotic letters in each of them. With these letters in hand, he could then go on to translate other names and words in the demotic passage.

But the process proved to be much more dif­ficult than de Sacy had anticipated. He succeeded in isolating the groups of demotic letters for the names of Ptolemy and Alexander, but found it impossible to identify the individual letters in the names. Eventually he gave up, say­ing, “The problem is too complicated, scientif­ically insoluble.”

A pupil of de Sacy’s, the Swedish diplomat Johan Akerblad, made better progress. Akerblad managed to locate in the demotic passage all the proper names that occurred in the Greek. From them he constructed a “demotic alphabet” of twenty-nine letters, almost half of which later proved to be correct.

—The Riddle of the Rosetta Stone,
James Cross Giblin

According to the passage, how did de Sacy and Akerblad influence each other’s work?

De Sacy was able to build on Akerblad’s work and make a demotic alphabet.
Akerblad built on de Sacy’s work and made a demotic alphabet.
Akerblad and de Sacy worked together to make a twenty-nine-letter demotic alphabet.
De Sacy was able to fix many mistakes that Akerblad made.