Which of the Following Was Not Known to Eighteenth- and Nineteenth-Century

Which of the following was not known to eighteenth- and nineteenth-century geologists?

A) Fossil organisms found in more recent strata resemble modern organisms more than those found in more ancient strata.
B) Fossils of similar organisms are found in widely separated places on Earth.
C) Radioactivity can be used to determine the age of rocks.
D) All of the above
E) None of the above