Physical Anthropologists Locating the Jaw Bones of Previously Unknown Vertebrate

Physical anthropologists locating the jaw bones of previously unknown vertebrate animal fossils are often able to assess the animal's diet especially because of clues from which of the following?

A) the position of muscle attachment sites
B) the prevalence of specific kinds of teeth
C) the size of the mouth opening
D) the evidence of food molecules still present
E) whether the mouth is the most anterior structure