What must the conclusion of the research paper do?
a. use source material
b. provide the writer's opinion
c. tie back to the thesis
d. grab the reader's interest

C.

The conclusion is the last part of your essay, so it should "sum up" the rest.

Here are the parts of an essay:

Introduction-Grab the reader's attention and introduce the topic.

Body Paragraphs-Use source material to prove your point.

Conclusion-Tie back to the introduction and thesis.

Hope I helped! :)