Answer :
It is important to verify every fact, idea, and argument that you find during research. This is especially true if you're using new or unreliable sources.
While doing research you apply sources. You use these sources for your main research idea. The sources are the previous works that have been done in this field. Complete Research means to confirm facts, reaffirm the previously done work, support theorems or develop new ideas. Therefore, the answer is verify.