Answer:
Option D
Step-by-step explanation:
Any change in the physical structure of any of the body part of living beings as a process of evolution is termed as structural adaptation. This adaptation makes an individual able to survive in the prevailing environmental condition.
Some common examples of structural adaptations are -
- Fur of bear
- Bill of bird
Of all given options, option D, -bill lengths of carnivores only depicts some change in the physical feature while rest all represent some change in functional features.
Therefore, option D is correct