Lightweight beaks, heavy teeth, stability in flight
The correct answer would be Fluoride was not used to help protect teeth then
Cavity is not a genetic disease and thus there is no relevance of gene transfer in this case. Thus option A, B and D gets ruled out.
However, flouride in a limited amount is very useful for removing the cavities. Flouride in the foood and water enters the blood stream and make the teeth strong from inside. While the Flouride in Saliva make the teeths stronger and cavity free from outside. It reduces reminization that causes the loss of minerals.
Thus lack of flouride makes the teeth more cavity prone.
