Answer
A. The Cristae of mitochondria is an example of a surface area adaptation
Explanation
The cristae in a mitochondrial are folds in the inner membrane which serve to increase the surface area. The more the folds of cristae in the mitochondrion the more locations for production of energy(ATP) to take place. When cristae folds are absent, the mitochondrion is unable to sustain the cell’s energy requirements.