Primates Are Difficult to Characterize as an Order Because____

Primates are difficult to characterize as an order because____.

A) they lack the strong specializations found in most other mammalian orders
B) they range in size from giant organisms to microscopic organisms
C) very few fossils have been found
D) species within this order breathe with both gills and lungs
E) they live in both the marine environment and the terrestrial environment