My English teacher says that the following is an "agreement" (which I assume means subject-verb agreement) error. He underlined the bolded parts of the sentence.
According to Political Research Associates, who used data gathered by the FBI, recorded hate crimes against Muslims increased by almost 1800% from 2000 to 2001 (Political Research Associates).
I've studied stuff online on subject verb agreements and cant find why this is an error. Could anyone help and maybe suggest a better sentence if this is wrong?