Why is C wrong? Thanks

Hi, I want to follow up on why C is wrong as well.

Hi I am not an instructor and I also got this question wrong the first time I did it but now I revisit this question, I understand why C is wrong and why the correct answer is E. The correct answer E states “Research suggests that the family of Puerto Rican Americans does not use code–switching in conversations held at home except for occasional rhetorical effect.” This is the correct summary of the last paragraph of the passage. C states “Research conducted prior to the study of a family of Puerto Rican Americans was thought by most researchers to explain code–switching in all except the most unusual or nonstandard contexts.” The topic of prior research prior to the study mentioned in the passage is not addressed anywhere in the passage. Thus, C is wrong because it is out of the scope. I hope that I explained it correct. Please feel free to correct me. Thank you