While a Great Many of the Fossils of Our Earliest

While a great many of the fossils of our earliest human ancestors have been found in Africa, why is it problematic to use these fossils to make concrete conclusions about our earliest origins?

A) There is unequal representation of time periods and species in the fossil record.
B) Dating techniques are still too primitive to establish completely accurate results.
C) Rival researchers often draw conflicting conclusions based on their discoveries.
D) Many parts of Africa cannot be easily accessed by paleoanthropologists.