GMAT Reading Comprehension (RC) | Re: The poetic expressiveness and creativity of Japanese women

Hi,
The time period being spoken is Heian period from 794-1140AD..
And it is mentioned that kana was used during this time.
So it supports that Kana was used in Japan after 793AD..

Don't confuse this with that kana started to be used after 793AD, then this will not hold support.
But Q talks ONLY about usage..