Answer:
(D). lungs
Step-by-step explanation:
Cladograms are diagrams that show cladistic relationship between organisms of different species on the basis of their characteristics. The cladograms may include characteristics to make two organisms different from each other.
In given cladogram, characteristic that separates bony fish from amphibians is 'lungs', as lungs are absent in bony fishes, while present in amphibians.
Thus, the correct answer is option (D).