In Paragraph 2, why does the author include the information that mud inside rhipidistian crossopterygian fossils differed in consistency and texture depending on where the mud was located? A. To provide evidence that rhipidistian crossopterygian lived in river channels and lakes on large deltas B. To identify an effect of the oxidation of iron minerals on the evolution of rhipidistian crossopterygian C. To help explain why scientists have concluded that rhipidistian crossopterygian probably had lungs D. To explain why scientists decided to cut cross sections through some fossils of rhipidistian crossopterygian