If the Genus Quercus (Oaks) Is Monophyletic, Then This Means

If the genus Quercus (oaks) is monophyletic, then this means that

A) all species of oaks grow in similar habitats.
B) oaks all have nearly identical appearance.
C) all species of oaks are descended from a common ancestor.
D) oaks cannot be classified in a single family or order.
E) all species of trees are classified as being in a single order.