C.
Every change in a species is coded within the DNA. But the bird had lost a toe an accident. So the toe-loosing-option isn't true because not every bird looses his toe.
(Example: If a women gets bitten by a snake on the arm and gets the arm removed from her body and then in a year or so has a baby with her new husband. The baby won't be born with one arm because his/her mother lost her arm.) <span />
Epiglottis
The epiglottis is a flap of cartilage the covers the entrance to the throat protecting the lungs from obstruction. It moves when we swallow to allow food in.
Activation energy is required to start a chemical reaction. Activation energy is the energy needed to allow the reactant to react. Activation energy is measured in Joules (J).