Veronica is writing a report on the various stages of digestion in the human body. She wants to know how the different organs contribute to this process. Which source would provide her with the necessary information?

*
a book titled Different Systems of the Human Body and How They Function
a blog post explaining the importance of eating fruits and vegetables for a healthy stomach
an article in a scientific journal titled "How Chemicals Used in Farming Cause Indigestion"
a video showing how the human body can breathe air and chew food at the same time

The most appropriate source for Veronica to gather information on the various stages of digestion in the human body and how different organs contribute to this process would be a book titled "Different Systems of the Human Body and How They Function." This source is likely to provide detailed and accurate information on the topic.