Critical Reasoning

When students receive positive feedback that focuses on getting a question correct or their perceived intelligence, they are less likely to attempt harder assignments than are students who are praised for their effort or the process they used. Because of this phenomenon, teachers who focus on effort and process are more likely to see better learning outcomes than those who focus on whether an individual question was correct or not.

Which of the following is an assumption on which the argument depends?

A. Students are more likely to learn from doing harder problems than they are to learn from easier ones.
B. Positive feedback is the best way to motivate students to learn.
C. Students can clearly articulate the difference between different types of positive feedback.
D. Feedback based on perceived intelligence is less favorable toward students than are other types of feedback.
E. The most important indicator of success is whether students are willing to attempt harder questions and assignments.

I'm unable to figure what's conclusion here. Also, how negation type can be applied here.

what is the answer