Are Nature Valley Protein Bars Vegan?

I am on a quest to adopt a vegan lifestyle and am currently examining the contents of my favorite snacks. One of my favorite snacks has been the Nature Valley Protein Bars. I am now wondering if the bars are vegan-friendly. Are all the ingredients plant-based, or are there any animal-derived ingredients, such as whey protein? I would appreciate it if someone with more knowledge on this subject could help me out.