Answer: C) What is the effect of vegetarianism on the human body?
Step-by-step explanation: when writing a research paper, it is really important to establish a research question that allows us to develop the subject and reach a conclusion. In the given prompt Julia is writing a research paper about vegetarianism, the research question that is her best option is "What is the effect of vegetarianism on the human body?" because the other options are questions with very specific answers and wouldn't allow her to develop the subject in her paper.