Do you think that the researchers of study added tenth and eighth graders to the survey deliberately? Support your answer with reference to the text.

Question :Do you think that the researchers of study added tenth and eighth graders to the survey deliberately? Support your answer with reference to the text.

The correct answer is -Yes, the researchers added tenth and eighth graders to the survey deliberately. This is stated in paragraph 3, which says, "While the study started with only twelfth-graders in the 1970s, eighth- and tenth-graders were added in 1991."