WANTED: Grammar Expert

[Cindy C.]

Hey,

I saw this in today's Washington Post, and I thought I'd test you 
guys.  Please, if you know the answer from reading about this in the 
media, let's keep the answer a secret and let folks who didn't read 
the story have a go.  

OK.  

A major standardized test in the U.S. asked students whether there 
was an error in grammar in the following sentence:

"Toni Morrison's genius enables her to create novels that arise from 
and express the injustices African Americans have endured."

Yes, there is an error (although the testing bureau denied that 
there was an scored "no error" as the correct answer).  A panel of 
outside experts in grammar was hired to rule, and they identified an 
error in grammar, forcing the testing bureau to re-score the exam.

What is the error?

Cindy -- who could not find the error