College board question that is strange??

[littlefry]

<p>The question was:
Whether the Sumerians (A. were) the first people (B. to develop) writing is (C. uncertain), but (D. theirs) is the oldest known writing system.
and the answer was no error. but why do they use theirs instead of it? It sounds so bizarre :\ </p>

[2016bostonian]

<p>“Sumerians” is plural, so therefore they use the plural “theirs”. They might have used “it’s” if they used, say, the Sumerian civilization instead of the Sumerians.</p>

[Bartleby007]

<p>

@2016bostonian

“Sumerians” is plural, so therefore they use the plural “theirs”. They might have used “it’s” if they used, say, the Sumerian civilization instead of the Sumerians.

@2016bostonian: “it’s” = “it is” and “its” is the possessive form of “it”</p>