The Heavy Wear Exhibited on Human Teeth Found in Natufian

The heavy wear exhibited on human teeth found in Natufian burials has been interpreted as evidence of:

A) the use of grinding stones in food preparation
B) an increase in periodontal disease resulting from an agricultural diet high in carbohydrates
C) use of the jaw in hide preparation
D) their having filed down their teeth to provide flat surfaces for eating tough cereal grains