Ms. Brown assigned a research project to her science students. The first step: decide on a problem and develop a research question. Sam decided on the following question: Do aliens live on Earth? Ms. Brown told Sam that his question and in general, his topic, were not suitable for a research project.
 Ms. Brown suggested to Sam that his topic was not suitable because he could not collect data or any _________ that aliens actually lived on Earth. What is the BEST term to fill in the blank from the choices below?
 A) evidence 
 B) photographs 
 C) proof 
 D) testimony