Sentence Correction (SC) | Re: During the same period in which the Maya were developing a

GMATNinja For option A, is the below substitution for "it" and "that" correct? If yes, then is it ok for "that" to refer "hieroglyphic system"? Isn't it far away.

During the same period in which the Maya were developing a hieroglyphic system of writing, the Aztec people also developed a written language, but it(written language) was not as highly sophisticated as that(hieroglyphic system) of the Maya and was more pictographic in nature.