GMAT Sentence Correction (SC) | Re: OG 2016 - With corn, soybean, and wheat reserves

Hi experts,

so far, idiom "so ...that..." or "...so that.." states a CE relationship for me.
I read the OE

that says "so..that.." is a tag of comparison, it is hard for me to understand.
appreciate if explain further

thanks a lot
have a nice day
>_~

---