Answer to Question 1
D
Answer to Question 2
Because the incomplete nature of the fossil record could lead to the absence of fossils of species that were present at a given time, paleontologists measure diversity changes by measuring the changes in diversity at higher taxonomic levels, such as changes in the number of families. The higher taxonomic levels should be less affected by the abundance of sedimentary rocks at a given time. Additionally, higher taxonomic levels are more stable and less likely to go extinct. For example, the extinction of a family requires extinction of all the genera within that family and every species within each of those genera. Therefore, it is more difficult for families to go extinct than it is for genera to go extinct, and it is more difficult for genera to go extinct than it is for species to go extinct.